LIGHT-EMITTING DIODE AND DISPLAY DEVICE COMPRISING SAME

A light emitting element includes: a first semiconductor layer doped with a first polarity; a second semiconductor layer doped with a second polarity different from the first polarity; an active layer between the first semiconductor layer and the second semiconductor layer in a first direction; and an insulating film surrounding an outer surface of at least the active layer and extending in the first direction. A thickness of a first portion of the insulating film surrounding the active layer is in a range of 10% to 16% of a diameter of the active layer.

BACKGROUND

The present disclosure relates to a light emitting element and a display device including the same.

2. Description of the Related Art

The importance of display devices has steadily increased with the development of multimedia technology. In response thereto, various types of display devices, such as an organic light emitting diode (OLED) display, a liquid crystal display (LCD), and the like have been developed.

A display device is a device for displaying (or configured to display) an image and generally includes a display panel, such as an organic light emitting diode display panel or a liquid crystal display panel. The light emitting display panel may include light emitting elements, for example, light emitting diodes (LED). Examples of the light emitting diode include an organic light emitting diode (OLED) using an organic material as a fluorescent material and an inorganic light emitting diode using an inorganic material as a fluorescent material.

Inorganic LEDs using an inorganic material (e.g., an inorganic semiconductor) as a fluorescent material are durable even in a high-temperature environment and have higher blue light efficiency than OLEDs. In addition, a transfer method using dielectrophoresis (DEP) has been developed for a manufacturing process to overcome limitations of conventional inorganic LEDs. Therefore, research is being continuously conducted on inorganic LEDs, which have better durability and efficiency than OLEDs.

SUMMARY

Aspects of the present disclosure provide a light emitting element including a thick electrode layer and a thick insulating film (e.g., a relatively thick electrode layer and a relatively thick insulating film) to protect an active layer.

Aspects of the present disclosure also provide a display device including the light emitting element and having improved luminous reliability.

It should be noted that aspects of the present disclosure are not limited thereto and other aspects, which are not mentioned herein, will be apparent to those of ordinary skill in the art from the following description.

According to an embodiment of the present disclosure, a light emitting element includes: a first semiconductor layer doped with a first polarity; a second semiconductor layer doped with a second polarity different from the first polarity; an active layer between the first semiconductor layer and the second semiconductor layer in a first direction; and an insulating film surrounding an outer surface of at least the active layer and extending in the first direction. A thickness of a first portion of the insulating film surrounding the active layer is in a range of 10% to 16% of a diameter of the active layer.

The diameter of the active layer may be in a range of 500 nm to 600 nm, and the thickness of the first portion of the insulating film may be in a range of 60 nm to 80 nm.

The insulating film may have a second portion extending from the first portion and covering a portion of a side surface of the second semiconductor layer, and a thickness of the second portion may be smaller than a thickness of the first portion.

A portion of the insulating film surrounding an interface between the active layer and the second semiconductor layer may have a thickness of at least 20 nm.

The second portion may have a curved outer surface such that its thickness decreases in the first direction.

The light emitting element may further include an electrode layer on the second semiconductor layer, and a thickness of the electrode layer may be greater than a thickness of the second semiconductor layer.

The electrode layer may have a thickness in a range of 20 nm to 200 nm.

The insulating film may surround a side surface of the electrode layer.

The insulating film may surround a portion of a side surface of the electrode layer, a top surface of the electrode layer may be exposed by the insulating film, and the side surface of the electrode layer may be partially exposed by the insulating film.

The insulating film may have a third portion connected to the first portion and surrounding a portion of the side surface of the electrode layer, and a thickness of the third portion may be smaller than a thickness of the first portion.

The third portion of the insulating film may have a curved outer surface such that its thickness decreases in the first direction.

According to an embodiment of the present disclosure, a display device includes: a substrate; a first electrode on the substrate and a second electrode spaced apart from the first electrode; a light emitting element between the first electrode and the second electrode and electrically connected to the first electrode and the second electrode; a first insulating layer under the light emitting element between the first electrode and the second electrode; and a second insulating layer on the light emitting element and exposing one end and another end of the light emitting element. The light emitting element includes: a first semiconductor layer doped with a first polarity; a second semiconductor layer doped with a second polarity different from the first polarity; an active layer between the first semiconductor layer and the second semiconductor layer in a first direction; and an insulating film surrounding an outer surface of at least the active layer and extending in the first direction. The insulating film includes a first portion surrounding the one end of the light emitting element and the active layer, a second portion contacting the second insulating layer, and a third portion surrounding the other end of the light emitting element, and a thickness of the second portion is greater than that of the first portion and the third portion.

The display device may further include: a first contact electrode contacting the first electrode and the one end of the light emitting element; and a second contact electrode contacting the second electrode and the other end of the light emitting element.

The light emitting element may further include an electrode layer on the second semiconductor layer and having a thickness greater than that of the second semiconductor layer. The first contact electrode may contact the first portion of the insulating film and the electrode layer, and the second contact electrode may contact the third portion of the insulating film and the first semiconductor layer.

The first portion of the insulating film may surround a portion of a side surface of the electrode layer, a top surface of the electrode layer may be exposed by the insulating film, and the side surface of the electrode layer may be partially exposed by the insulating film.

The first contact electrode may contact a portion of the side surface and the top surface of the electrode layer.

The first portion of the insulating film may have a curved outer surface such that its thickness decreases in the first direction.

In the first portion, a first thickness measured at an interface between the second semiconductor layer and the electrode layer and a second thickness measured at an interface between the second semiconductor layer and the active layer may satisfy the following Equation (1):

wherein: θc is an inclination angle of an inclined outer surface of the first portion of the insulating film; W1′ is a thickness measured at an interface between the electrode layer and the second semiconductor layer in the first portion of the insulating film; W2′ is a thickness measured at an interface between the second semiconductor layer and the active layer in the first portion of the insulating film; and D is a thickness of the second semiconductor layer.

The second thickness may be 20 nm or more, and a thickness of the first portion surrounding the active layer may be 40 nm or more.

The electrode layer may have a thickness in a range of 20 nm to 200 nm.

A thickness of the second portion may be in a range of 10% to 16% of a diameter of the active layer.

The diameter of the active layer may be in a range of 500 nm to 600 nm, and the thickness of the second portion of the insulating film may be in a range of 60 nm to 80 nm.

A first diameter of the light emitting element measured at the second portion of the insulating film may be greater than a second diameter of the light emitting element measured at the first portion of the insulating film and a third diameter of the light emitting element measured at the third portion of the insulating film.

Details of other embodiments are included in the detailed description and the accompanying drawings.

A light emitting element, according to one embodiment of the present disclosure, includes an electrode layer having a thickness greater than that of a second semiconductor layer and an insulating film in which a portion surrounding the active layer has a thickness of a certain level or more. The light emitting element may prevent the electrode layer from being removed during a manufacturing process and may safely protect the active layer even if the insulating film is partially etched.

Accordingly, the display device according to embodiments of the present disclosure including the light emitting element may exhibit improved luminous efficiency and luminous reliability.

The aspects and features according to the embodiments of the present disclosure are not limited by those described above, and other various aspects and features are included in this disclosure and will be understood by those of ordinary skill in the art.

DETAILED DESCRIPTION

FIG. 1is a schematic plan view of a display device according to one embodiment.

Referring toFIG. 1, a display device10displays (e.g., is configured to display) a moving image and/or a still image. The display device10may refer to any electronic device including a display screen. Examples of the display device10may include a television, a laptop computer, a monitor, a billboard, an Internet-of-Things (loT) device, a mobile phone, a smartphone, a tablet personal computer (PC), an electronic watch, a smart watch, a watch phone, a head-mounted display, a mobile communication terminal, an electronic notebook, an electronic book, a portable multimedia player (PMP), a navigation device, a game machine, a digital camera, a camcorder, and the like that include a display screen.

The display device10includes a display panel which provides a display screen. Examples of the display panel may include an LED display panel, an organic light emitting diode display panel, a quantum dot light emitting display panel, a plasma display panel, and a field emission display panel. In the following description, an example in which the display panel is an LED display panel will be described, but the present disclosure is not limited thereto, and other display panels may be applied within the same scope of the present disclosure.

The shape of the display device10may be variously modified. For example, the display device10may have a shape, such as a rectangular shape elongated in a horizontal direction, a rectangular shape elongated in a vertical direction, a square shape, a quadrilateral shape with rounded corners (e.g., vertices), another polygonal shape, and a circular shape. The shape of a display area DA of the display device10may be similar to the overall shape of the display device10. InFIG. 1, the display device10and the display area DA have a rectangular shape elongated in the horizontal direction.

The display device10may have the display area DA and a non-display area NDA. The display area DA is an area where an image can be displayed, and the non-display area NDA is an area where an image is not displayed. The display area DA may also be referred to as an active region, and the non-display area NDA may also be referred to as a non-active region.

The display area DA may substantially occupy the center of the display device10. The display area DA may include a plurality of pixels PX. The plurality of pixels PX may be arranged in a matrix. The shape of each pixel PX may be a rectangular or square shape in a plan view. However, the present disclosure is not limited thereto, and each pixel PX may have a rhombic shape in which each side is inclined with respect to one direction. Each of the pixels PX may include one or more light emitting elements300that emit light of a specific wavelength band to display a specific color.

FIG. 2is a schematic plan view of one pixel of a display device according to one embodiment.FIG. 3is a plan view illustrating one sub-pixel shown inFIG. 2.

Referring toFIGS. 2 and 3, each of the pixels PX may include a first sub-pixel PX1, a second sub-pixel PX2, and a third sub-pixel PX3. The first sub-pixel PX1may emit light of a first color, the second sub-pixel PX2may emit light of a second color, and the third sub-pixel PX3may emit light of a third color. The first color may be blue, the second color may be green, and the third color may be red. However, the present disclosure is not limited thereto, and the sub-pixels PXn may emit the same color light. In addition, althoughFIG. 2illustrates an embodiment in which the pixel PX includes three sub-pixels PXn, the present disclosure is not limited thereto, and the pixel PX may include a greater number of sub-pixels PXn.

Each sub-pixel PXn of the display device10may include a region defined as an emission area EMA. The first sub-pixel PX1may include a first emission area EMA1, the second sub-pixel PX2may include a second emission area EMA2, and the third sub-pixel PX3may include a third emission area EMA3. The emission area EMA may be defined as a region where the light emitting elements300included in the display device10are disposed to emit light of a specific wavelength band. The light emitting element300includes an active layer330, and the active layer330may emit light of a specific wavelength band without directionality. Light emitted from the active layer330of the light emitting element300may be radiated in a lateral direction of the light emitting element300as well as in directions of both ends (e.g., opposite ends) of the light emitting element300. The emission area EMA of each sub-pixel PXn may include a region adjacent to the light emitting element300where the light emitted from the light emitting element300is radiated, including the region where the light emitting element300is disposed. Further, without being limited thereto, the emission area EMA may also include a region where the light emitted from the light emitting element300is reflected or refracted by another member and emitted. The plurality of light emitting elements300may be disposed in the respective sub-pixels PXn, and the emission area EMA may include an area where the light emitting element300is disposed and an area adjacent thereto.

Each sub-pixel PXn of the display device10may include a non-emission area defined as a region other than the emission area EMA. The non-emission area may be a region in which the light emitting element300is not disposed and a region from which light is not emitted because light emitted from the light emitting element300does not reach it.

Each sub-pixel PXn of the display device10may include a plurality of electrodes210and220, the light emitting element300, a plurality of contact electrodes260, and a plurality of external banks430. The display device10may further include a plurality of internal banks410and420and a plurality of insulating layers510,520,530and550(see, e.g.,FIG. 4).

The plurality of electrodes210and220may include a first electrode210and a second electrode220. The first and second electrodes210and220may include respective electrode stems210S and220S arranged to extend in a first direction DR1and respective electrode branches210B and220B extending from the respective electrode stems210S and220S in a second direction DR2crossing (e.g., intersecting) the first direction DR1.

The first electrode210may include the first electrode stem210S extending in the first direction DR1, and at least one electrode branch210B branched from (e.g., branched off from) the first electrode stem210S and extending in the second direction DR2.

The first electrode stems210S of any one pixel may be arranged such that both ends of the individual first electrode stems210S are terminated with gaps between the respective sub-pixels PXn, and each first electrode stem210S may be arranged along substantially a same straight line as the first electrode stem210S of the sub-pixel adjacent to it in the same row (e.g., in the first direction DR1). Because the first electrode stems210S disposed in the respective sub-pixels PXn are arranged such that both ends thereof are spaced apart from each other (e.g., are physically and electrically disconnected or isolated from each other), different electric signals may be applied to the first electrode branches210B in different sub-pixels PXn.

The first electrode branch210B may be branched from at least a part of the first electrode stem210S, may extend in the second direction DR2and may be terminated while being spaced apart from the second electrode stem220S, which is disposed to face the first electrode stem210S.

The second electrode220may include the second electrode stem220S extending in the first direction DR1and disposed to face the first electrode stem210S while being distanced (e.g., spaced) apart from it in the second direction DR2; and the second electrode branch220B may be branched from the second electrode stem220S and may extend in the second direction DR2. The second electrode stem220S may be connected at the other end to the second electrode stem220S of another sub-pixel PXn adjacent to it in the first direction DR1. That is, different from the first electrode stem210S, the second electrode stem220S may extend in the first direction DR1across the respective sub-pixels PXn. The second electrode stem220S that is elongated (or extends) across the respective sub-pixels PXn may be connected to an outer part of the display area DA where the respective pixels PX or sub-pixels PXn are arranged or to an extension portion extended from the non-display area NDA in one direction.

The second electrode branch220B may be disposed to face the first electrode branch210B with a gap therebetween and may be terminated while being spaced apart from the first electrode stem210S. The second electrode branch220B may be connected to the second electrode stem220S, and an end of the second electrode branch220B in the extension direction (e.g., a distal end of the electrode branch220B) may be disposed within the sub-pixel PXn while being spaced apart from the first electrode stem210S.

The first electrode210and the second electrode220may be electrically connected to the conductive layer of a circuit element layer PAL (see, e.g.,FIG. 4) of the display device10through contact openings (e.g., contact holes), including a first electrode contact hole CNTD and a second electrode contact hole CNTS, respectively. The second electrode contact hole CNTD is illustrated as being formed at every first electrode stem210S of each sub-pixel PXn, while only one second electrode contact hole CNTS is illustrated as being formed at the single second electrode stem220S, which is elongated across the respective sub-pixels PXn. However, the present disclosure is not limited thereto, and in some embodiments, the second electrode contact hole CNTS may be formed for each sub-pixel PXn.

The electrodes210and220may be electrically connected to the light emitting elements300and may receive a voltage applied thereto to allow the light emitting elements300to emit light in a specific wavelength band. Further, at least a part (or portion) of each of the electrodes210and220may be used to form an electric field within the sub-pixel PXn to align the light emitting elements300.

In an embodiment, the first electrode210may be a pixel electrode which is separated for each sub-pixel PXn, and the second electrode220may be a common electrode connected along the respective sub-pixels PXn to be shared by them. One of the first and second electrodes210and220may be an anode electrode of the light emitting element300, and the other of the first and second electrodes210and220may be a cathode electrode of the light emitting element300.

The illustrated embodiment includes two first electrode branches210B disposed in each sub-pixel PXn and one second electrode branch220B disposed therebetween. However, the layout of the first and second electrode branches210B and220B may not be limited thereto. In some embodiments, the first electrode210and the second electrode220may have a shape without the electrode stems210S and220S and extending in the second direction DR2. Further, the first and second electrodes210and220may not necessarily have a shape extending in one direction and may have various layouts. For example, the first electrode210and the second electrode220may have a partially curved or bent shape, and one electrode may be disposed to surround (e.g., to extend around a periphery of) the other electrode. The layout and the shape of the first and second electrodes210and220may not be particularly limited as long as at least some portions thereof face each other with a gap therebetween, creating a space where the light emitting elements300may be disposed.

The external banks430may be disposed at the boundaries between the sub-pixels PXn. Each external bank430may extend in the second direction DR2to be disposed at the boundary between the adjacent sub-pixels PXn that are arranged in (e.g., adjacent to each other in) the first direction DR1. The first electrode stems210S may be terminated such that their respective ends are spaced apart from each other with the external banks430therebetween. However, the present disclosure is not limited thereto, and the external bank430may extend in the first direction DR1to be disposed at the boundary between the adjacent sub-pixels PXn that are arranged in the second direction DR2. The external banks430may include the same material as the internal banks410and420, to be described later, and the external and internal banks may be formed concurrently (or simultaneously) in one process.

The light emitting elements300may be disposed between the first electrode210and the second electrode220. The light emitting element300may be electrically connected to the first electrode210at one end thereof and the second electrode220at the other end thereof. The light emitting element300may be electrically connected to each of the first electrode210and the second electrode220through the contact electrode260.

The plurality of light emitting elements300may be spaced apart from each other and aligned substantially parallel to each other. The interval between the light emitting elements300is not particularly limited. In some embodiments, multiple light emitting elements300may be disposed adjacent to each other to form a group, and other light emitting elements300may be arranged while being spaced apart from each other at a regular distance to form another group. For example, the light emitting elements300may be arranged in different densities but they may be still aligned in one direction. Further, in an embodiment, the light emitting element300may have a shape extending in one direction, and the extension direction of the electrodes, for example, the first electrode branch210B and the second electrode branch220B, may be substantially perpendicular to the extension direction of the light emitting element300. However, the present disclosure is not limited thereto, and the light emitting element300may be disposed diagonally with respect to the extension direction of the first electrode branch210B and the second electrode branch220B, not perpendicularly thereto.

The light emitting elements300according to one embodiment may have active layers330including different materials and, thus, may emit lights of different wavelength bands to the outside. The display device10according to one embodiment may include the light emitting elements300that emit light of different wavelength bands. The light emitting element300of the first sub-pixel PX1may include the active layer330that emits a first light L1having a central wavelength band of a first wavelength, the light emitting element300of the second sub-pixel PX2may include the active layer330that emits a second light L2having a central wavelength band of a second wavelength, and the light emitting element300of the third sub-pixel PX3may include the active layer330that emits a third light L3having a central wavelength band of a third wavelength.

Accordingly, the first light Ll may be emitted from the first sub-pixel PX1, the second light L2may be emitted from the second sub-pixel PX2, and the third light L3may be emitted from the third sub-pixel PX3. In some embodiments, the first light L1may be blue light having a central wavelength band in a range of about 450 nm to about 495 nm, the second light L2may be green light having a central wavelength band in a range of about 495 nm to about 570 nm, and the third light L3may be red light having a central wavelength band in a range of about 620 nm to about 752 nm.

However, the present disclosure is not limited thereto. In some embodiments, the first sub-pixel PX1, the second sub-pixel PX2, and the third sub-pixel PX3may include the light emitting elements300of the same type (e.g., having the same active layer330) to emit light of substantially the same color.

The light emitting element300according to one embodiment may include a semiconductor core and an insulating film380(see, e .g.,FIG. 5) surrounding the semiconductor core. The semiconductor core may include a plurality of semiconductor layers310and320and an active layer330disposed therebetween. The light emitting element300may have one end electrically connected to the first electrode210and the other end electrically connected to the second electrode220to receive electric signals, and the light emitting element300that has received the electric signals may generate light in the active layer330and emit it to the outside. The insulating film380surrounding the semiconductor core of the light emitting element300may be disposed to surround (e.g., cover) at least the outer surface of the active layer330and protect it. The light emitting element300according to one embodiment may include the insulating film380having a thickness of a certain level or more sufficient to prevent the active layer330of the light emitting element300from being damaged during the manufacturing process of the light emitting element300and the manufacturing process of the display device10and to improve element reliability.

Further, the semiconductor core of the light emitting element300may further include an electrode layer370(see, e.g.,FIG. 5) disposed on the second semiconductor layer320, and the light emitting element300may be electrically connected to the first electrode210or the second electrode220through the electrode layer370. The light emitting element300according to one embodiment may include the electrode layer370having a thickness of a certain level or more sufficient to prevent the electrode layer370of the light emitting element300from being removed during the manufacturing process of the light emitting element300, thereby improving the element efficiency. A detailed description thereof will be given later.

The plurality of contact electrodes260may have a shape in which at least a partial region thereof extends in one direction. Each of the plurality of contact electrodes260may contact the light emitting element300and the electrodes210and220, and the light emitting elements300may receive the electrical signals from the first electrode210and the second electrode220through the contact electrode260.

The contact electrode260may include a first contact electrode261and a second contact electrode262. The first contact electrode261and the second contact electrode262may be disposed on the first electrode branch210B and the second electrode branch220B, respectively.

The first contact electrode261may be disposed on the first electrode210or the first electrode branch210B and may extend in the second direction DR2to contact one end of the light emitting element300. The second contact electrode262may be spaced apart from the first contact electrode261in the first direction DR1, may be disposed on the second electrode220or the second electrode branch220B, and may extend in the second direction DR2to contact the other end of the light emitting element300. The first contact electrode261and the second contact electrode262may contact the first electrode210and the second electrode220exposed through openings of the second insulating layer520. The light emitting element300may be electrically connected to the first electrode210and the second electrode220through the first contact electrode261and the second contact electrode262.

In some embodiments, the widths of the first contact electrode261and the second contact electrode262measured in one direction may be respectively greater than the widths of the first electrode210and the second electrode220or the widths of the first electrode branch210B and the second electrode branch220B measured in the one direction. The first contact electrode261and the second contact electrode262may be disposed to cover the side portions of the first electrode210and the second electrode220or the side portions of the first electrode branch210B and the second electrode branch220B. However, the present disclosure is not limited thereto, and in some embodiments, the first contact electrode261and the second contact electrode262may be disposed to cover only one side portion of the first electrode branch210B and the second electrode branch220B.

Although the illustrated embodiment includes two first contact electrodes261and one second contact electrode262disposed in one sub-pixel PXn, the present disclosure is not limited thereto. The number of the first contact electrode261and the second contact electrode262may vary depending on the number of the first electrode(s)210and the second electrode(s)220disposed in each sub-pixel PXn or the number of the first electrode branch(es)210B and the second electrode branch(es)220B.

The display device10may further include the circuit element layer PAL positioned under the electrodes210and220and a plurality of insulating layers disposed thereon. Hereinafter, the stacked structure of the display device10will be described in more detail with reference toFIG. 4.

FIG. 4only shows a cross section of the first sub-pixel PX1, but the same description may be applied to other pixels PX or sub-pixels PXn.FIG. 4shows a cross section passing through one end and the other end of the light emitting element300disposed in the first sub-pixel PX1.

Referring toFIG. 4in conjunction withFIGS. 2 and 3, the display device10may include the circuit element layer PAL and an emission layer EML. The circuit element layer PAL may include a substrate110, a buffer layer115, a light blocking layer BML, conductive wires191and192, first and second transistors120and140, and the like, and the emission layer EML may include the above-described plurality of electrodes210and220, the light emitting element300, the plurality of contact electrodes261and262, the plurality of insulating layers510,520,530,550, and the like.

The substrate110may be an insulating substrate. The substrate110may include (or may be made of) an insulating material, such as glass, quartz, or polymer resin. Further, the substrate110may be a rigid substrate, but may be, in other embodiments, a flexible substrate that can be bent, folded, or rolled.

The light blocking layer BML may be disposed on the substrate110. The light blocking layer BML may include a first light blocking layer BML1and a second light blocking layer BML2. The first light blocking layer BML1may be electrically connected with a first source electrode123of the first transistor120, to be described later. The second light blocking layer BML2may be electrically connected with a second source electrode143of the second transistor140.

The first light blocking layer BML1and the second light blocking layer BML2are arranged to overlap a first active material layer126of the first transistor120and a second active material layer146of the second transistor140, respectively. The first and second light blocking layers BML1and BML2may include a material that blocks light and, thus, can prevent (or substantially prevent) light from reaching the first and second active material layers126and146. For example, the first and second light blocking layers BML1and BML2may be formed of an opaque metal material that blocks light transmission. However, the present disclosure is not limited thereto, and in some embodiments, the light blocking layer BML may be omitted.

The buffer layer115is disposed on the light blocking layer BML and the substrate110. The buffer layer115may be disposed to cover the entire surface of the substrate110, including the light blocking layer BML. The buffer layer115can prevent diffusion of impurity ions, prevent penetration of moisture or external air, and perform a surface planarization function. Furthermore, the buffer layer115may insulate the light blocking layer BML and the first and second active material layers126and146from each other.

A semiconductor layer is disposed on the buffer layer115. The semiconductor layer may include the first active material layer126of the first transistor120, the second active material layer146of the second transistor140, and an auxiliary layer163. The semiconductor layer may include polycrystalline silicon, monocrystalline silicon, oxide semiconductor, and the like.

The first active material layer126may include a first doped region126a,a second doped region126b,and a first channel region126c.The first channel region126cmay be disposed between the first doped region126aand the second doped region126b. The second active material layer146may include a third doped region146a,a fourth doped region146b,and a second channel region146c.The second channel region146cmay be disposed between the third doped region146aand the fourth doped region146b.The first active material layer126and the second active material layer146may include polycrystalline silicon. The polycrystalline silicon may be formed by crystallizing amorphous silicon. Examples of the crystallizing method may include rapid thermal annealing (RTA), solid phase crystallization (SPC), excimer laser annealing (ELA), metal-induced lateral crystallization (MILC), and sequential lateral solidification (SLS) but are not limited thereto. As another example, the first active material layer126and the second active material layer146may include monocrystalline silicon, low-temperature polycrystalline silicon, amorphous silicon, or the like. The first doped region126a,the second doped region126b,the third doped region146a,and the fourth doped region146bmay be areas of the first active material layer126and the second active material layer146doped with impurities. However, the present disclosure is not limited thereto.

The first active material layer126and the second active material layer146are not necessarily limited to the above-described embodiments. In an embodiment, the first active material layer126and the second active material layer146may include an oxide semiconductor. In such an embodiment, the first doped region126aand the third doped region146amay be a first conductive region, and the second doped region126band the fourth doped region146bmay be a second conductive region. When the first active material layer126and the second active material layer146include an oxide semiconductor, the oxide semiconductor may be an oxide semiconductor including (or containing) indium (In). In some embodiments, the oxide semiconductor may be indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium oxide (IGO), indium zinc tin oxide (IZTO), indium gallium tin oxide (IGTO), indium gallium zinc tin oxide (IGZTO), or the like. However, the present disclosure is not limited thereto.

A first gate insulating film150is disposed on the semiconductor layer. The first gate insulating film150may be disposed to cover the entire surface of the buffer layer115, including the semiconductor layer. The first gate insulating film150may act as a gate insulating film for the first and second transistors120and140.

A first conductive layer is disposed on the first gate insulating film150. The first conductive layer may include a first gate electrode121disposed on the first active material layer126of the first transistor120, a second gate electrode141disposed on the second active material layer146of the second transistor140, and a wiring pattern161disposed on the auxiliary layer163on the first gate insulating film150. The first gate electrode121may overlap the first channel region126cof the first active material layer126, and the second gate electrode141may overlap the second channel region146cof the second active material layer146.

An interlayer insulating film170is disposed on the first conductive layer. The interlayer insulating film170may act as an insulating film between the first conductive layer and other layers disposed thereon. In addition, the interlayer insulating film170may include (or contain) an organic insulating material and may also perform a surface planarization function.

A second conductive layer is disposed on the interlayer insulating film170. The second conductive layer includes the first source electrode123and the first drain electrode124of the first transistor120, the second source electrode143and the second drain electrode144of the second transistor140, and a power electrode162disposed on the wiring pattern161.

The first source electrode123and the first drain electrode124may contact the first doped region126aand the second doped region126bof the first active material layer126, respectively, via contact openings (e.g., contact holes) formed through the interlayer insulation film170and the first gate insulating film150. The second source electrode143and the second drain electrode144may contact the third doped region146aand the fourth doped region146bof the second active material layer146, respectively, via contact openings (e.g., contact holes) formed through the interlayer insulation film170and the first gate insulating film150. Further, the first source electrode123and the second source electrode143may be electrically connected to the first light blocking layer BML1and the second light blocking layer BML2, respectively, via other contact openings (e.g., other contact holes).

A passivation film180may be disposed on the second conductive layer. The passivation film180may be disposed to cover the second conductive layer and may be disposed on the entire interlayer insulating film170. For example, the passivation film180may be disposed to cover the first source electrode123, the first drain electrode124, the second source electrode143, and the second drain electrode144.

A conductive wiring layer may be disposed on the passivation film180. The conductive wiring layer may include the first conductive wire191and the second conductive wire192, and they may be electrically connected to the first source electrode123of the first transistor120and the power electrode162, respectively.

The conductive wiring layer may also be electrically connected to the first electrode210and the second electrode220of the emission layer EML and may transmit electrical signals applied from the first transistor120and the power electrode162to the electrodes210and220.

A first insulating layer510is disposed on the conductive wiring layer. The first insulating layer510includes (or contains) an organic insulating material and may perform a surface planarization function.

The plurality of internal banks410and420, the external bank430(see, e.g.,FIG. 4), the plurality of electrodes210and220, and the light emitting element300may be disposed on the first insulating layer510.

As described above, the external bank430may extend in the first direction DR1or the second direction DR2to be disposed at the boundary between the sub-pixels PXn. For example, the external bank430may delimit the boundary of each sub-pixel PXn.

The external banks430may prevent ink from going over the boundaries of the sub-pixels PXn when the ink is deposited (e.g., jetted) in which the light emitting elements300are dispersed using an inkjet printing device in the manufacture of the display device10. The external bank430may separate inks in which different light emitting elements300are dispersed for different sub-pixels PXn so they are not mixed with each other. However, the present disclosure is not limited thereto.

The plurality of internal banks410and420may be disposed to be spaced apart from each other in each sub-pixel PXn. The multiple internal banks410and420may include the first internal bank410and the second internal bank420disposed adjacent to the center of each sub-pixel PXn.

The first internal back410and the second internal bank420are disposed to face each other. The first electrode210may be disposed on the first internal bank410, and the second electrode220may be disposed on the second internal bank420. As shown inFIGS. 3 and 4, the first electrode branch210B is disposed on the first internal bank410, and the second electrode branch220B is disposed on the second internal bank420.

Similar to the first electrode210and the second electrode220, the first internal bank410and the second internal bank420may be disposed to extend in the second direction DR2in each sub-pixel PXn. The first internal bank410and the second internal bank420may extend in the second direction DR2toward the sub-pixels PXn adjacent thereto in the second direction DR2. However, the present disclosure is not limited thereto, and the first internal bank410and the second internal bank420may be disposed in each of the sub-pixels PXn separately, forming a pattern on (or over) the entire surface of the display device10.

Each of the first internal bank410and the second internal bank420may have a structure with at least a part thereof protruding above the first insulating layer510. Each of the first internal bank410and the second internal bank420may protrude above the plane on which the light emitting element300is disposed, and at least a part of this protruding portion may have a slope. The shape of the protruding portions of the first and second internal banks410and420is not particularly limited. Because the internal banks410and420protrude with respect to the first insulating layer510and have inclined side surfaces, light emitted from the light emitting element300may be reflected by the inclined side surfaces of the internal banks410and420. As will be described later, when the electrodes210and220disposed on the internal banks410and420include a material having high reflectivity, light emitted from the light emitting element300may be reflected by the electrodes210and220positioned on the inclined side surfaces of the internal banks410and420and travel in an upward direction of the first insulating layer510.

For example, the external bank430may delimit adjacent sub-pixels PXn and may prevent ink from overflowing to an adjacent sub-pixels PXn in an inkjet process, and the internal banks410and420may have a protruding structure in each sub-pixel PXn and act as a reflective partition wall for reflecting light emitted from the light emitting element300in the upward direction of the first insulating layer510. However, the present disclosure is not limited thereto. The plurality of internal banks410and420and external banks430may include, but are not limited to, polyimide (PI).

The plurality of electrodes210and220may be disposed on the first insulating layer510and the internal banks410and420, respectively. As stated above, the electrodes210and220include the electrode stems210S and220S and the electrode branches210B and220B, respectively. The line Xa-Xa′ ofFIG. 3crosses the first electrode stem210S, the line Xb-Xb′ ofFIG. 3crosses the first and second electrode branches210B and220B, and the line Xc-Xc′ ofFIG. 3extends along the second electrode stem220S. The first electrode210disposed in the area Xa-Xa′ inFIG. 4can be understood to be the first electrode stem210S; the first electrode210and the second electrode220disposed in the area Xb-Xb′ inFIG. 4can be understood to be the first electrode branch210B and the second electrode branch220B, respectively; and the second electrode220disposed in the area Xc-Xc′ inFIG. 4can be understood to be the second electrode stem220S. The electrode stems210S and the electrode branch210B may from (or may constitute) the first electrode210, and the electrode stem220S and the electrode branch220B may form (or may constitute) the second electrode220.

Some areas of the first and second electrodes210and220may be disposed on the first insulating layer510and some other areas thereof may be disposed on the first and second internal banks410and420, respectively. For example, the widths of the first electrode210and the second electrode220may be greater than the widths of the internal banks410and420. Parts of the bottom surfaces of the first electrode210and the second electrode220may contact the first insulating layer510, and other parts thereof may contact the internal banks410and420.

The first electrode stem210S of the first electrode210and the second electrode stem220S of the second electrode220, which extend in the first direction DR1, may partially overlap the first internal bank410and the second internal bank420, respectively. However, the present disclosure is not limited thereto, and the first electrode stem210S and the second electrode stem220S may not overlap (e.g., may be offset from) the first internal bank410and the second internal bank420, respectively.

The first electrode contact hole CNTD may be formed in the first electrode stem210S of the first electrode210to penetrate the first insulating layer510and expose a part of the first conductive wire191. The first electrode210may contact the first conductive wire191through the first electrode contact hole CNTD, and the first electrode210may be electrically connected to the first source electrode123of the first transistor120to receive an electrical signal.

The second electrode contact hole CNTS may be formed in the second electrode stem220S of the second electrode220to penetrate the first insulating layer510and expose a part of the second conductive wire192. The second electrode220may contact the second conductive wire192through the second electrode contact hole CNTS, and the second electrode220may be electrically connected to the power electrode162to receive an electrical signal.

Some areas of the first electrode210and the second electrode220, for example, the first electrode branch210B and the second electrode branch220B, may be disposed to cover the first internal bank410and the second internal bank420, respectively. The first electrode210and the second electrode220may face each other with a gap therebetween, and the plurality of light emitting elements300may be disposed therebetween.

Each of the electrodes210and220may include a transparent conductive material. For example, each of the electrodes210and220may include a material, such as indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO), but they are not limited thereto. In some embodiments, each of the electrodes210and220may include a conductive material having high reflectivity. For example, each of the electrodes210and220may include, as a material having high reflectivity, a metal, such as silver (Ag), copper (Cu), or aluminum (Al). In such an embodiment, light incident to each of the electrodes210and220may be reflected to be radiated in an upward direction from each sub-pixel PXn.

Further, each of the electrodes210and220may have a structure in which at least one transparent conductive material and at least one metal layer having high reflectivity are stacked or may be formed as one layer including them. In an embodiment, each of the electrodes210and220may have a stacked structure of ITO/silver (Ag)/ITO/IZO or may include (or may be made of) an alloy including aluminum (Al), nickel (Ni), and/or lanthanum (La). However, the present disclosure is not limited thereto.

The second insulating layer520is disposed on the first insulating layer510, the first electrode210, and the second electrode220. The second insulating layer520is disposed to partially cover the first electrode210and the second electrode220. The second insulating layer520may be disposed to cover most of the top surfaces of the first electrode210and the second electrode220, and the openings exposing parts of the first electrode210and the second electrode220may be formed in the second insulating layer520. The openings in the second insulating layer520may be positioned to expose the relatively flat top surfaces of the first electrode210and the second electrode220.

In an embodiment, the second insulating layer520may be formed to have a step such that a portion of the top surface thereof is recessed between the first electrode210and the second electrode220. In some embodiments, the second insulating layer520may include (or contain) an inorganic insulating material, and a part of the top surface of the second insulating layer520disposed to cover the first electrode210and the second electrode220may be recessed by the step formed by the electrodes210and220. The light emitting element300disposed on the second insulating layer520between the first electrode210and the second electrode220may form an empty space with respect to the recessed top surface of the second insulating layer520. The light emitting element300may be disposed partially spaced apart from the top surface of the second insulating layer520with a space (e.g., a clearance) therebetween, and this space may be filled with a material forming the third insulating layer530, to be described later.

However, the present disclosure is not limited thereto. The second insulating layer520may include a flat top surface with the light emitting element300disposed thereon. The top surface may extend in one direction toward the first electrode210and the second electrode220and may be terminated on inclined side surfaces of the first electrode210and the second electrode220. For example, the second insulating layer520may be disposed in an area where the electrodes210and220overlap the inclined side surfaces of the first internal bank410and the second internal bank420, respectively. The contact electrode260may contact the exposed areas of the first and second electrodes210and220and may smoothly contact an end of the light emitting element300on the flat top surface of the second insulating layer520.

The second insulating layer520may protect the first electrode210and the second electrode220while insulating them from each other. Further, the light emitting element300disposed on the second insulating layer520may not be damaged by direct contact with other members. However, the shape and structure of the second insulating layer520are not limited thereto.

The light emitting element300may be disposed on the second insulating layer520between the electrodes210and220. For example, at least one light emitting element300may be disposed on the second insulating layer520disposed between the electrode branches210B and220B. However, the present disclosure is not limited thereto, and at least some of the light emitting elements300disposed in each sub-pixel PXn may be in a region other than the region between the electrode branches210B and220B. Further, the light emitting element300may be disposed such that some areas thereof overlap the electrodes210and220. The light emitting element300may be disposed on ends where the first electrode branch210B and the second electrode branch220B face each other.

In the light emitting element300, a plurality of layers may be disposed in a direction parallel to the first insulating layer510. The light emitting element300according to one embodiment may have a shape extending in one direction and may have a structure in which a plurality of semiconductor layers are sequentially arranged in one direction. In the light emitting element300, the first semiconductor layer310, the active layer330, the second semiconductor layer320, and the electrode layer370may be sequentially disposed along one direction, and the outer surfaces thereof may be surrounded (e.g., covered) by the insulating film380. The light emitting element300may be disposed in the display device10such that one extension direction is parallel to the first insulating layer510, and the plurality of semiconductor layers included in the light emitting element300may be sequentially disposed along the direction parallel to the top surface of the first insulating layer510. However, the present disclosure is not limited thereto. In some embodiments, when the light emitting element300has a different structure, a plurality of layers may be arranged in a direction perpendicular to the first insulating layer510.

Further, one end of the light emitting element300may contact the first contact electrode261, and the other end thereof may contact the second contact electrode262. According to one embodiment, because the end surfaces of the light emitting element300in the direction in which it extends are exposed without the insulating film380formed thereon, the light emitting element300may contact the first contact electrode261and the second contact electrode262at the exposed regions. However, the present disclosure is not limited thereto. In some embodiments, in the light emitting element300, at least some regions of the insulating film380may be removed (or omitted), and the insulating film380may be removed (or formed) to partially expose both end side surfaces of the light emitting element300. During the manufacturing process of the display device10, in the step of forming the third insulating layer530covering the outer surface of the light emitting element300, the insulating film380may be partially removed. The exposed side surfaces of the light emitting element300may contact the first contact electrode261and the second contact electrode262. However, the present disclosure is not limited thereto.

The third insulating layer530may be partially disposed on the light emitting element300disposed between the first electrode210and the second electrode220. The third insulating layer530may be disposed to partially surround the outer surface of the light emitting element300to protect the light emitting element300and may fix the light emitting element300during the manufacturing process of the display device10. According to one embodiment, the third insulating layer530may be disposed on the light emitting element300and may expose one end and the other end of the light emitting element300. The exposed ends (e.g., the one end and the other end) of the light emitting element300may contact the contact electrode260so that electrical signals may be received from the electrodes210and220. The shape of the third insulating layer530may be formed by a patterning process using a material forming the third insulating layer530using a conventional mask process. The mask for forming the third insulating layer530may have a width smaller than the length of the light emitting element300, and the material forming the third insulating layer530may be patterned such that both ends of the light emitting element300are exposed. However, the present disclosure is not limited thereto.

Further, in an embodiment, a portion of the material of the third insulating layer530may be disposed between the bottom surface of the light emitting element300and the second insulating layer520. The third insulating layer530may be formed to fill a space between the second insulating layer520and the light emitting element300formed during the manufacturing process of the display device10. Accordingly, the third insulating layer530may be formed to surround the outer surface of the light emitting element300. However, the present disclosure is not limited thereto.

The third insulating layer530may extend in the second direction DR2between the first electrode branch210B and the second electrode branch220B in a plan view. For example, the third insulating layer530may have an island shape or a linear shape on the first insulating layer510in a plan view.

The first contact electrode261is disposed on the electrode210and the third insulating layer530, and the second contact electrode262is disposed on the second electrode220and the third insulating layer530. The third insulating layer530may be disposed between the first contact electrode261and the second contact electrode262and may insulate them from each other to prevent direct contact between the first contact electrode261and the second contact electrode262.

As described above, the first contact electrode261and the second contact electrode262may contact at least one end of the light emitting element300, and the first contact electrode261and the second contact electrode262may be electrically connected to the first electrode210or the second electrode220to receive an electrical signal.

The first contact electrode261may contact the exposed area of the first electrode210on the first internal bank410, and the second contact electrode262may contact the exposed area of the second electrode220on the second internal bank420. The first contact electrode261and the second contact electrode262may respectively transmit electrical signals transmitted from the electrodes210and220to the light emitting element300.

The contact electrode260may include a conductive material. For example, they may include ITO, IZO, ITZO, aluminum (Al), or the like. However, the present disclosure is not limited thereto.

A passivation layer550may be disposed on the contact electrode260and the third insulating layer530. The passivation layer550may protect the members disposed on the first insulating layer510from the external environment.

Each of the first insulating layer510, the second insulating layer520, the third insulating layer530, and the passivation layer550described above may include an inorganic insulating material or an organic insulating material. In an embodiment, the first insulating layer510, the second insulating layer520, the third insulating layer530, and the passivation layer550may include an inorganic insulating material, such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum oxide (AlxOy), aluminum nitride (AIN), and the like. The first insulating layer510, the second insulating layer520, the third insulating layer530, and the passivation layer550may include an organic insulating material, such as acrylic resin, epoxy resin, phenolic resin, polyamide resin, polyimide resin, unsaturated polyester resin, polyphenylene resin, polyphenylene sulfide resin, benzocyclobutene, cardo resin, siloxane resin, silsesquioxane resin, polymethylmethacrylate, polycarbonate, and polymethylmethacrylate-polycarbonate synthetic resin. However, the present disclosure is not limited thereto.

The display device10according to one embodiment may include the light emitting element300including the electrode layer370and the insulating film380, each having a thickness of a certain level or more. According to one embodiment, the active layer330of the light emitting element300may not be damaged and/or the electrode layer370may not be removed during the manufacturing process of the light emitting element300and the manufacturing process of the display device10, and the light emitting element300may exhibit improved luminous efficiency and luminous reliability. Hereinafter, the light emitting element300according to embodiments of the present disclosure will be described in detail with reference to other drawings.

FIG. 5is a schematic diagram of a light emitting element according to one embodiment.FIG. 6is a schematic cross-sectional view of a light emitting element according to one embodiment.

A light emitting element300may be a light emitting diode. For example, the light emitting element300may be an inorganic light emitting diode that has a micrometer or nanometer size and including (or made of) an inorganic material. The inorganic light emitting diode may be aligned between two electrodes having polarity when an electric field is formed in a specific direction between the two opposing electrodes. The light emitting element300may be aligned between the two electrodes by the electric field generated between the electrodes.

The light emitting element300according to one embodiment may have a shape extending in one direction. The light emitting element300may have a shape of a rod, wire, tube, or the like. In an embodiment, the light emitting element300may have a cylindrical or rod shape. However, the shape of the light emitting element300is not limited thereto, and the light emitting element300may have a polygonal prism shape, such as a regular cube, a rectangular parallelepiped, and a hexagonal prism, or may have various suitable shapes, such as a shape extending in one direction and having partially inclined outer surface. A plurality of semiconductors included in the light emitting element300, to be described later, may have a structure in which they are sequentially arranged or stacked along the one direction.

The light emitting element300may include a semiconductor layer doped with any conductivity type (e.g., p-type or n-type) impurities. The semiconductor layer may emit light of a specific wavelength band by receiving an electrical signal applied from an external power source.

The light emitting element300according to one embodiment may emit light of a specific wavelength band. In an embodiment, the active layer330may emit blue light having a central wavelength band ranging from about 450 nm to about 495 nm. However, it should be understood that the central wavelength band of blue light is not limited to the above-mentioned range but includes all wavelength ranges that can be recognized as blue in the pertinent art. Further, the light emitted from the active layer330of the light emitting element300may not be limited thereto and may be emit green light having a central wavelength band ranging from about 495 nm to about 570 nm or may emit red light having a central wavelength band ranging from about 620 nm to about 750 nm. Hereinafter, the description will be provided on the assumption that the light emitting element300emits blue light as an example.

Referring toFIGS. 5 and 6, the light emitting element300may include the semiconductor core and the insulating film380surrounding (e.g., extending around or covering) the semiconductor core, and the semiconductor core of the light emitting element300may include the first semiconductor layer310, the second semiconductor layer320, and the active layer330. Further, the light emitting element300according to one embodiment may further include the electrode layer370disposed on one surface of the first semiconductor layer310or the second semiconductor layer320.

The first semiconductor layer310may be an n-type semiconductor. For example, when the light emitting element300emits light of a blue wavelength band, the first semiconductor layer310may include a semiconductor material having a chemical formula of AlxGayIn1−x−yN (0≤x+y≤1). For example, the semiconductor material may be any one or more of n-type doped AlGaInN, GaN, AlGaN, InGaN, AlN, and InN. The first semiconductor layer310may be doped with an n-type dopant. For example, the n-type dopant may be Si, Ge, Sn, or the like. In an embodiment, the first semiconductor layer310may be n-GaN doped with n-type Si. The length of the first semiconductor layer310may be in a range of about 1.5 μm to about 5 μm but is not limited thereto.

The second semiconductor layer320is disposed on the active layer330. The second semiconductor layer320may be a p-type semiconductor. For example, when the light emitting element300emits light of a blue or green wavelength band, the second semiconductor layer320may include a semiconductor material having a chemical formula of AlxGayIn1−x−yN (0≤x≤1, 0≤y≤1, 0≤x+y≤1). For example, the second semiconductor layer320may be any one or more of p-type doped AlGaInN, GaN, AIGaN, InGaN, AIN and InN. The second semiconductor layer320may be doped with a p-type dopant. For example, the p-type dopant may be Mg, Zn, Ca, Se, Ba, or the like. In an embodiment, the second semiconductor layer320may be p-GaN doped with p-type Mg. The length of the second semiconductor layer320may be in a range of about 0.05 μm to about 0.10 μm but is not limited thereto.

Although the first semiconductor layer310and the second semiconductor layer320in the illustrated embodiment are a single layer, the present disclosure is not limited thereto. According to some embodiments, depending on the material of the active layer330, the first semiconductor layer310and the second semiconductor layer320may have a greater number of layers, such as a cladding layer or a tensile strain barrier reducing (TSBR) layer. A description thereof will be given later with reference to other drawings.

The active layer330is disposed between the first semiconductor layer310and the second semiconductor layer320. The active layer330may include a material having a single or multiple quantum well structure. When the active layer330includes a material having a multiple quantum well structure, a plurality of quantum layers and well layers may be alternately stacked. The active layer330may emit light by the coupling of electron-hole pairs according to an electrical signal applied through the first semiconductor layer310and the second semiconductor layer320. For example, when the active layer330emits light of a blue wavelength band, a material such as AIGaN or AlGaInN may be included. When the active layer330has a multiple quantum well structure in which quantum layers and well layers are alternately stacked in, the quantum layer may include a material, such as AIGaN or AlGaInN, and the well layer may include a material, such as GaN or AlInN. In an embodiment, as described above, the active layer330includes AlGaInN as a quantum layer and AlInN as a well layer, and the active layer330may emit blue light having a central wavelength band of 450 nm to 495 nm.

However, the present disclosure is not limited thereto, and the active layer330may have a structure in which semiconductor materials having large band gap energy and semiconductor materials having small band gap energy are alternately stacked, and the semiconductor materials may include other group III to V semiconductor materials according to the wavelength band of the emitted light. The light emitted by the active layer330is not limited to light of a blue wavelength band, and the active layer330may also emit light of a red or green wavelength band in different embodiments. The length of the active layer330may be in a range of about 0.05 μm to about 0.10 μm, but it is not limited thereto.

Light emitted from the active layer330may be emitted to both side surfaces as well as the outer surface of the light emitting element300in a longitudinal direction. The directionality of the light emitted from the active layer330is not limited to one direction.

The electrode layer370may be an ohmic contact electrode. However, the present disclosure is not limited thereto, and electrode layer370may be a Schottky contact electrode. The light emitting element300may include at least one electrode layer370. AlthoughFIG. 6illustrates that the light emitting element300includes one electrode layer370, the present disclosure is not limited thereto. In some embodiments, the light emitting element300may include a greater number of electrode layers370, or the electrode layer370may be omitted. The following description of the light emitting element300may be equally applied even when the number of electrode layers370is different or further includes other structures.

In the display device10according to an embodiment, when the light emitting element300is electrically connected to an electrode or a contact electrode, the electrode layer370may reduce the resistance between the light emitting element300and the electrode or contact electrode. The electrode layer370may include a conductive metal. For example, the electrode layer370may include at least one of aluminum (Al), titanium (Ti), indium (In), gold (Au), silver (Ag), indium tin oxide (ITO), indium zinc oxide (IZO), or indium tin zinc oxide (ITZO). Further, the electrode layer370may include an n-type or p-type doped semiconductor material. The electrode layer370may include the same material or different materials, but it is not limited thereto.

In the light emitting element300, the electrode layer370may be partially etched during the manufacturing process. As will be described later, in the process of forming the insulating film380, the electrode layer370may be partially etched to have a thickness smaller than an initial thickness. In the light emitting element300, the electrode layer370may have a thickness of a certain level or more to prevent the electrode layer370from being etched and removed during the above process. In the light emitting element300according to one embodiment, the thickness of the electrode layer370may be within a range of about 20 nm to about 200 nm or, in one embodiment, within a range of about 100 nm to about 200 nm. When the electrode layer370has a thickness smaller than about 20 nm, the electrode layer370may be etched and removed in the process of forming the insulating film380or contact failure with the second semiconductor layer320may occur. And when the thickness of the electrode layer370is about 200 nm or more, the light generated in the active layer330may be absorbed by the electrode layer370so that the optical characteristics of the light emitting element300may deteriorate. Accordingly, the electrode layer370of the light emitting element300may have a thickness of about 20 nm or more, and in some embodiments, may be within a range of about 100 nm to about 200 nm.

In the light emitting element300, the light generated in the active layer330may be emitted through both end surfaces (e.g., the top surface of the electrode layer370or the bottom surface of the first semiconductor layer310). The transmittance of the light generated in the active layer330may vary depending on the thickness of the electrode layer370. However, the light emitting element300according to one embodiment may include the electrode layer370having a thickness within the above-described range and have the transmittance of a certain level or more. For example, when the active layer330generates blue light having a central wavelength band of about 450 nm, the electrode layer370may have the transmittance of 65% or more or 70% or more with respect to the light having the central wavelength band of about 450 nm. However, the present disclosure is not limited thereto.

Furthermore, in the light emitting element300, because the electrode layer370has the thickness within the above-described range, the change in the transmittance with respect to the thickness may be reduced or minimized. For example, when the electrode layer370has a thickness of about 20 nm to about 200 nm, or about 100 nm to about 200 nm, the change in the transmittance with respect to the light having the central wavelength band of about 450 nm may be about 3% or about 1%. Accordingly, in the light emitting element300, the thickness of the electrode layer370may be controlled to prevent the electrode layer370from being removed during the manufacturing process of the display device10, and the emission characteristics and the element efficiency may be improved due to it having the transmittance of a certain level or more.

Further, in some embodiments, the electrode layer370of the light emitting element300may have a thickness greater than that of the second semiconductor layer320. Due to the larger thickness of the electrode layer370, the electrode layer370may smoothly contact the second semiconductor layer320or the first contact electrode261. In some embodiments, the electrode layer370of the light emitting element300may be formed to be thicker than the second semiconductor layer320. However, the present disclosure is not limited thereto.

The insulating film380is disposed to surround the outer surfaces of the above-described semiconductor core and electrode layer. In an embodiment, the insulating film380may be arranged to surround at least the outer surface of the active layer330and extend along the extension direction of the light emitting element300. The insulating film380may protect the members. For example, the insulating film380may be formed to surround side surfaces of the members while exposing both ends of the light emitting element300in the longitudinal direction.

Although the insulating film380extends in the longitudinal direction of the light emitting element300to cover a region from the first semiconductor layer310to the side surface of the electrode layer370in the illustrated embodiment, the present disclosure is not limited thereto. The insulating film380may cover only the outer surfaces of some semiconductor layers, including the active layer330, or may cover only a part of the outer surface of the electrode layer370to partially expose the outer surface of each electrode layer370. Further, in a cross-sectional view, the insulating film380may have a top surface, which is rounded in a region adjacent to at least one end of the light emitting element300.

The insulating film380may include materials having insulating properties, for example, silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum nitride (AlN), aluminum oxide (AxOy), and the like. Accordingly, an electrical short circuit that may occur when the active layer330directly contacts the electrode through which the electrical signal is transmitted to the light emitting element300may be prevented. In addition, because the insulating film380protects the outer surface of the light emitting element300including the active layer330, degradation in luminous efficiency may be avoided.

Further, in some embodiments, the insulating film380may have an outer surface which is surface-treated. When the display device10is manufactured, the light emitting elements300may be aligned by being sprayed on the electrodes in a state of being dispersed in an ink (e.g., a predetermined ink). The surface of the insulating film380may be treated to have a hydrophobic property or hydrophilic property to keep the light emitting element300in the dispersed state without being aggregated with other neighboring light emitting elements300in the ink.

The light emitting element300may have a length in a range of about 1 μm to about 10 μm or about 2 μm to about 6 μm, and in one embodiment, in a range of about 3 μm to about 5 μm. Further, a diameter of the light emitting element300may be in a range of about 300 nm to about 700 nm, and an aspect ratio of the light emitting element300may be about 1.2 to about 100. However, the present disclosure is not limited thereto, and the plurality of light emitting elements300included in the display device10may have different diameters according to a difference in composition of the active layer330. In one embodiment, the diameter of the light emitting element300may be in a range of about 500 nm.

The insulating film380may include at least the active layer330to protect the semiconductor core of the light emitting element300. As described above, during the manufacturing process of the light emitting element300and the manufacturing process of the display device10, the insulating film380may be partially etched to have a reduced thickness. When the insulating film380has the reduced thickness, the insulating film380may be etched and removed during the manufacturing process, or the semiconductor core, such as, the active layer330, may be damaged. The insulating film380of the light emitting element300according to one embodiment may have a thickness of a certain level or more.

In the light emitting element300according to one embodiment, the insulating film380may have a thickness within a range of about 10 nm to about 1.0 μm, within a range of about 20 nm to about 80 nm, or, in one embodiment, within a range of about 60 nm to about 80 nm. The insulating film380may have the thickness within the above-described range and may be disposed to surround at least the outer surface of the active layer330. Accordingly, even if the insulating film380is partially etched during the manufacturing process of the light emitting element300and the manufacturing process of the display device10, the insulating film380may remain on the outer surface of the active layer330and protect it. Although the insulating film380is disposed to surround the entire outer surface of the semiconductor core including the active layer330and is disposed to surround the side surfaces of the first semiconductor layer310and the electrode layer370in the illustrated embodiment, the present disclosure is not limited thereto. In the light emitting element300, the insulating film380may not be disposed and the outer surface of the semiconductor core may be partially exposed.

Because the insulating film380has the thickness within the above-described range, the diameter of the semiconductor core and the thickness of the insulating film380may have a relationship in the light emitting element300. For example, in the light emitting element300, the thickness of the insulating film380may be within the range of about 10% to about 16% of the diameter of the semiconductor core. When the insulating film380has the thickness within the above-described range, the semiconductor core, including the active layer330, may be protected.

Further, in some embodiments, the insulating film380may be disposed along the outer surface of the semiconductor core but may not have a uniform thickness. The insulating film380may have different thicknesses on the outer surfaces of the first semiconductor layer310, the active layer330, the second semiconductor layer320, and the electrode layer370. The different thicknesses may be because the insulating film380is etched during the manufacturing process of the light emitting element300or is partially etched after the light emitting element300is disposed on the display device10to have different thicknesses depending on positions.

FIG. 7is an enlarged view of the area QA ofFIG. 4.

FIG. 7is an enlarged cross-sectional view illustrating the light emitting element300disposed between the first electrode210and the second electrode220in the display device10. Referring toFIG. 7, the light emitting element300may be disposed on the second insulating layer520between the first electrode210and the second electrode220. The light emitting element300may include, on the outer surface of the insulating film380, one side surface that is a lower surface and the other side surface that is an upper surface in a cross-sectional view. The one side surface may contact the second insulating layer520and the third insulating layer530disposed on the lower side of the light emitting element300and the other side surface may contact the insulating layer530and the contact electrode260disposed on the upper side of the light emitting element300.

The one side surface, that is, the lower surface, of the light emitting element300may contact the second insulating layer520and may contact the third insulating layer530in the space formed by partially recessing the second insulating layer520and filled with the third insulating layer530. The one side surface, that is, the lower surface, of the light emitting element300in a cross-sectional view may not be etched during the manufacturing process of the display device10. Accordingly, the contact surface between the second insulating layer520and the third insulating layer530may form a flat surface.

On the other hand, in the light emitting element300, the other side surface, that is, the upper surface in a cross-sectional view, may be partially etched in the etching process performed before the process of forming the contact electrode260.

On the other side surface, the insulating film380may be etched in the region contacting the contact electrode260except (other than) the portion contacting the third insulating layer530. The display device10according to one embodiment may include the region in which the thickness of the insulating film380of the light emitting element300is partially different. The other side surface may include a first surface (e.g., a first surface portion)51in contact with the first contact electrode261, a second surface (e.g., a second surface portion) S2in contact with the second contact electrode262, and a third surface (e.g., a third surface portion) S3in contact with the third insulating layer530. The first surface S1and the second surface S2may be partially etched before the process of forming the contact electrode260so that the insulating film380may have a relatively small thickness at these portions, and the third surface S3may contact the third insulating layer530so that the insulating film380may not be etched at this portion. Accordingly, the insulating film380may have a smaller thickness in the regions corresponding to the first surface S1and the second surface S2than in the region corresponding to the third surface S3.

The thickness of the insulating film380of the light emitting element300may be the thickness of the region where the third surface S3is positioned. For example, the light emitting element300of the display device10may have a thickness within the range of about 60 nm to about 80 nm in the region of the insulating film380where the third surface S3is positioned (e.g., in the region in contact with the third insulating layer530). On the other hand, the thickness of the light emitting element300may be within the range of about 40 nm to about 60 nm in the regions where the first surface51and the second surface S2are positioned (e.g., in the regions in contact with the first contact electrode261and the second contact electrode262).

Accordingly, the light emitting element300disposed between the first electrode210and the second electrode220may have different diameters depending on positions. For example, the light emitting element300may have different diameters measured in another direction perpendicular to the one extension direction.

For example, a first diameter Da of the light emitting element300measured in the other direction in the region where the third surface S3is positioned may be greater than a second diameter Db measured in the region where the second surface S2is positioned and a third diameter Dc measured in the region where the first surface S1is positioned. At least some of the first diameter Da, the second diameter Db, and the third diameter Dc may have different values because the insulating film380is partially etched during the manufacturing process of the display device10or the manufacturing process of the light emitting element300.

Further, in the light emitting element300, in the region where the first surface51is positioned, a third-first diameter Dc1, measured at the interface between the active layer330and the second semiconductor layer320, and a third-second diameter Dc2, measured at the interface between the second semiconductor layer320and the electrode layer370, may be further defined. Although the third-first diameter Dc1and the third-second diameter Dc2are equal in the illustrated embodiment, the present disclosure is not limited thereto. In some embodiments, the third-first diameter Dc1and the third-second diameter Dc2may have different values, and the insulating film380may be formed to have an inclined outer surface in a cross-sectional view. A description thereof may be provided with reference to other embodiments.

The region of the insulating film380where the first surface S1is positioned (e.g., the region in contact with the first contact electrode261) may be the region surrounding the active layer330and may have a thickness of a certain level or more. The insulating film380of the light emitting element300according to one embodiment may have a thickness within a range of about 60 nm to about 80 nm, and at least some regions may have a thickness of about 40 nm or more and about 60 nm or less. In the region of the insulating film380where the first surface S1is positioned, such as in the region surrounding the active layer330, the insulating film380may have the thickness of about 40 nm or more even if it is partially etched during the manufacturing process so that exposure of the active layer330of the light emitting element300may be prevented. Because the insulating film380is formed to have a thickness of a certain level or more during the manufacturing process of the light emitting element300, the light emitting element300disposed in the display device10may protect the active layer330even when the insulating film380is partially etched. Accordingly, the luminous efficiency and the luminous reliability of the light emitting element300may be improved.

The display device10may further include a greater number of insulating layers. According to one embodiment, the display device10may further include a fourth insulating layer540disposed to protect the first contact electrode261.

FIG. 8is a cross-sectional view illustrating a part of a display device according to one embodiment.

Referring toFIG. 8, the display device10according to one embodiment may further include the fourth insulating layer540disposed on the first contact electrode261. The display device10shown inFIG. 8is different from the display device10shown inFIG. 4in that it further includes the fourth insulating layer540and at least a part of the second contact electrode262is disposed on the fourth insulating layer540. In the following description, redundant descriptions will be omitted.

The display device10shown inFIG. 8may include the fourth insulating layer540that is disposed on the first contact electrode261and that electrically insulates the first contact electrode261and the second contact electrode262from each other. The fourth insulating layer540may be arranged to cover the first contact electrode261and not to overlap (e.g., and offset from) a partial region of the light emitting element300such that the light emitting element300is connected to the second contact electrode262. The fourth insulating layer540may partially contact the first contact electrode261and the third insulating layer530on the top surface of the third insulating layer530. The fourth insulating layer540may be disposed on the third insulating layer530to cover one end of the first contact electrode261. Accordingly, the fourth insulating layer540may protect the first contact electrode261and electrically insulate it from the second contact electrode262.

A side surface of the fourth insulating layer540in a direction in which the second contact electrode262is disposed may be aligned with one side surface of the third insulating layer530. However, the present disclosure is not limited thereto. In some embodiments, the fourth insulating layer540may include (or contain) an inorganic insulating material, similar to the second insulating layer520.

The first contact electrode261may be disposed between the first electrode210and the fourth insulating layer540, and the second contact electrode262may be disposed on the fourth insulating layer540. The second contact electrode262may partially contact the second insulating layer520, the third insulating layer530, the fourth insulating layer540, the second electrode220, and the light emitting element300. One end of the second contact electrode262in a direction in which the first electrode210is disposed may be disposed on the fourth insulating layer540.

The passivation layer550may be disposed on the fourth insulating layer540and the second contact electrode262to protect them. Hereinafter, redundant descriptions will be omitted.

Hereinafter, a manufacturing process of the light emitting element300according to one embodiment will be described.

FIGS. 9 to 14are cross-sectional views showing steps of a manufacturing process of a light emitting element according to one embodiment.

First, referring toFIG. 9, a lower substrate1000including a base substrate1100and a buffer material layer1200formed on the base substrate1100is prepared. The base substrate1100may include a transparent substrate, such as a sapphire (A1203) substrate and a glass substrate. However, the present disclosure is not limited thereto, and the base substrate1100may be formed of a conductive substrate, such as GaN, SiC, ZnO, Si, GaP and GaAs. The following description is directed to an embodiment where the base substrate1100is a sapphire (A1203) substrate. Although not limited thereto, the base substrate1100may have, for example, a thickness in the range of about 400 μm to about 1500 μm.

A plurality of semiconductor layers are formed on the base substrate1100.

The plurality of semiconductor layers grown by an epitaxial method may be formed by growing seed crystals. The semiconductor layer may be formed using one of electron beam deposition, physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma laser deposition (PLD), dual-type thermal evaporation, sputtering, and metal organic chemical vapor deposition (MOCVD). In one embodiment, the metal organic chemical vapor deposition (MOCVD) process may be used. However, the present disclosure is not limited thereto.

Typically, a precursor material for forming the plurality of semiconductor layers may be selected to form a target material in a typically selectable range without limitation. For example, the precursor material may be a metal precursor including an alkyl group, such as a methyl group or an ethyl group. Examples of the precursor material may include, but are not limited to, trimethylgallium (Ga(CH3)3), trimethylaluminum (Al(CH3)3), and triethyl phosphate ((C2H5)3PO4). Hereinafter, a description is made of the processing order of the method for manufacturing the light emitting element300and the layered structure of the light emitting element300in detail.

A buffer material layer1200is formed on the base substrate1100. Although one buffer material layer1200is deposited in the illustrated embodiment, the present disclosure is not limited thereto, and a plurality of layers may be formed. The buffer material layer1200may be disposed to reduce a difference in lattice constant between a first semiconductor3100and the base substrate1100.

For example, the buffer material layer1200may include an undoped semiconductor and may be a material including substantially the same material as the first semiconductor3100and neither n-type doped nor p-type doped. In an embodiment, the buffer material layer1200may be, but is not limited to, at least one of undoped InAlGaN, GaN, AlGaN, InGaN, AlN, or InN. The buffer material layer1200may be omitted depending on the base substrate1100. The following description will be given for an example where the buffer material layer1200including an undoped semiconductor is formed on the base substrate1100.

Next, as shown inFIG. 10, the semiconductor structure3000is formed on the underlying substrate1000. The semiconductor structure3000may include a first semiconductor3100, an active layer3300, a second semiconductor3200, and an electrode material layer3700. The plurality of material layers included in the semiconductor structure3000may be formed by performing the typical processes as stated above, and the plurality of layers included in the semiconductor structure3000may correspond to the respective layers included in the light emitting element300according to one embodiment. For exampe, the plurality of material layers may include the same materials as the first semiconductor layer310, the active layer330, the second semiconductor layer320, and the electrode layer370of the light emitting element300.

Next, referring toFIG. 11, the semiconductor structure3000is etched to form semiconductor cores3000′ spaced apart from each other. The semiconductor structure3000may be etched by a conventional method. For example, the semiconductor structure3000may be etched by a method of forming an etch mask layer thereon and etching the semiconductor structure3000along the etch mask layer in a direction perpendicular to the lower substrate1000.

For example, the process of etching the semiconductor structure3000may be dry etching, wet etching, reactive ion etching (RIE), inductively coupled plasma reactive ion etching (ICP-RIE), or the like. The dry etching method may be suitable for vertical etching because anisotropic etching can be performed. When using the aforementioned etching technique, Cl2or O2may be used as an etchant. However, the present disclosure is not limited thereto.

In some embodiments, etching the semiconductor structure3000may be carried out with a combination of the dry etching and the wet etching. For example, etching may be performed in a depth direction with the dry etching and then anisotropic etching with the wet etching such that the etched sidewalls are on a plane perpendicular to the surface.

Next, an element rod ROD including the insulating film380partially surrounding the outer surface of the semiconductor core3000′ is formed.

Referring toFIGS. 12 and 13, the insulating film380may be formed by forming an insulating coating film3800surrounding the outer surface of the semiconductor core3000′ and then partially removing the insulating coating film3800to expose one end of the semiconductor core3000′ (e.g., the top surface of the electrode layer370) (see, e.g.,1st etch inFIG. 12).

The insulating coating film3800, that is, an insulating material, formed on the outer surface of the semiconductor core3000′ may be formed by using a method of coating or immersing an insulating material on the outer surface of the vertically etched semiconductor core3000′. However, the present disclosure is not limited thereto. For example, the insulating coating film3800may be formed by using atomic layer deposition (ALD).

The insulating coating film3800may also be formed on the side surfaces and the top surfaces of the semiconductor cores3000′ and on the lower substrate1000exposed in the region where the semiconductor cores3000′ are spaced apart from each other. The partial removal of the insulating coating film3800may be carried out by etch-back or dry etching as anisotropic etching. In the drawing, the upper surface of the insulating coating film3800is removed to expose the electrode layer370, and in this process, the electrode layer370may also be partially removed. For example, in the light emitting element300, the thickness of the electrode layer370of the light emitting element300that is manufactured may be smaller than the thickness of the electrode material layer3700formed during the manufacturing process. As described above, the thickness of the electrode material layer3700may be about 200 nm or more to form the electrode layer370of the light emitting element300having the thickness of about 20 nm to about 200 nm or about 100 nm to about 200 nm. However, the present disclosure is not limited thereto.

Although it is illustrated in the drawing that the top surface of the electrode layer370is exposed and the upper surface of the insulating film380is flat, the present disclosure is not limited thereto. In some embodiments, the insulating film380may be formed to have a partially curved outer surface in an area where it surrounds the electrode layer370. In the process of partially removing the insulating coating film3800, a side surface of the insulating coating film3800as well as the top surface thereof may be partially removed so that the insulating film380surrounding the multiple layers may be formed with a partially etched end surface. or example, as the top surface of the insulating coating film3800is removed, an outer surface of the insulating film380adjacent to the electrode layer370may be partially removed in the light emitting element300.

Finally, as shown inFIG. 14, the light emitting element300is manufactured by separating the element rod ROD on which the insulating film380is formed from the lower substrate1000.

Through the above-described processes, the light emitting element300according to one embodiment may be manufactured. The light emitting element300manufactured as described above may be disposed between the first electrode210and the second electrode220, and the display device10may be manufactured by arranging the third insulating layer530, the contact electrode260, and the like thereon. Next, the manufacturing process of the display device10will be described with further reference to other drawings.

FIGS. 15 to 19are cross-sectional views illustrating steps of a manufacturing process of a display device according to one embodiment.

First, referring toFIG. 15, the first insulating layer510, the first internal bank410and the second internal bank420spaced apart from each other on the first insulating layer510, the first electrode210and the second electrode220respectively disposed on the first internal bank410and the second internal bank420, and a second insulating layer520′ covering the first electrode210and the second electrode220are prepared. The second insulating material layer520′ may be partially patterned in a subsequent process to form the second insulating layer520of the display device10. The above members may be formed by patterning a metal, an inorganic material, or an organic material by performing a conventional mask process.

Next, an ink900including the light emitting elements300is deposited (e.g., sprayed) on the first electrode210and the second electrode220. The ink900may include a solvent910and the light emitting elements300dispersed in the solvent910. The light emitting elements300may be sprayed on the electrodes210and220while being dispersed in the solvent910and may be aligned between the first electrode210and the second electrode220by an electrical signal applied in a subsequent process.

Next, referring toFIG. 16, the electrical signals may be applied to the first electrode210and the second electrode220to generate an electric field on the ink900including the light emitting elements300. The light emitting elements300may receive a dielectrophoretic force induced by the electric field and may be arranged between the first electrode210and the second electrode220while the orientations and positions thereof are being changed.

Next, referring toFIG. 17, the solvent910of the ink900is removed. Accordingly, the light emitting element300is disposed between the first electrode210and the second electrode220, and the plurality of light emitting elements300mounted between the first electrode210and the second electrode220may be aligned with a specific orientation.

Next, referring toFIGS. 18 and 19, a third insulating material layer530′ is formed to cover the second insulating material layer520′ and the light emitting element300and then patterned to form the third insulating layer530(see, e.g., 2ndetch inFIG. 18). The third insulating material layer530′ may be partially patterned by the etching process (e.g., the 2ndetch) to form the third insulating layer530. In the etching process (e.g., the 2ndetch) of the third insulating material layer530′, the outer surface of the light emitting element300may be partially exposed, and the insulating film380may be partially etched at this time. Accordingly, the exposed portion of the insulating film380where the third insulating layer530is not disposed (e.g., the region where the first surface S1and the second surface S2shown inFIG. 7are positioned) may have a thickness smaller than that of the third surface S3, that is, the portion in contact with the third insulating layer530.

Thereafter, the second insulating material layer520′ may be patterned to form the second insulating layer520, and the first contact electrode261and the second contact electrode262and the passivation layer550may be formed to manufacture the display device10.

As described above, the light emitting element300and the display device10according to one embodiment may be manufactured. The electrode layer370of the light emitting element300may be partially etched and may have a reduced thickness during the manufacturing process of the light emitting element300, and the insulating film380of the light emitting element300may be partially etched and may have a reduced thickness during the manufacturing process of the light emitting element300and the manufacturing process of the display device10. The light emitting element300according to one embodiment may include the electrode layer370and the insulating film380, each having a thickness of a certain level or more, to protect the active layer330and allow smooth contact between the electrode layer370and the second semiconductor layer320. Accordingly, the light emitting element300included in the display device10may secure excellent luminous efficiency and luminous reliability.

Hereinafter, the light emitting element300and the display device10according to various embodiments will be described.

FIG. 20is a schematic cross-sectional view of a light emitting element according to one embodiment.

Referring toFIG. 20, in a light emitting element300_1according to one embodiment, an insulating film380_1may have a partially inclined top surface or end surface and may include regions having different thicknesses. The light emitting element300_1shown inFIG. 20is different from the light emitting element300shown inFIG. 6in that the end surface of the insulating film380_1has the inclined shape. In addition, the arrangement and structures of the electrode layer370, the first semiconductor layer310, the active layer330, and the like are the same as those ofFIG. 6, and differences between these embodiments will be primarily described.

According to one embodiment, the insulating film380_1may be disposed to expose a part of the semiconductor core, such as the side surface of an electrode layer370_1, and the end surface of the portion of the insulating film380_1where the electrode layer370_1is exposed may have a partially inclined shape. The outer surface of the electrode layer370_1may include, on the outer surface thereof, a first exposed surface370S1that is exposed without the insulating film380_1formed thereon and a second exposed surface370S2, that is, the other surface opposed to one surface in contact with a second semiconductor layer320_1. The first exposed surface370S1and the second exposed surface370S2, which are the exposed surfaces without the insulating film380_1formed thereon, may be exposed in the process of etching the insulating coating film3800during the manufacturing process of the light emitting element300_1. In the light emitting element300shown inFIG. 6, only the top surface of the electrode layer370is exposed in the process of etching the insulating coating film3800. However, in the light emitting element300_1shown inFIG. 20, the first exposed surface370S1of the electrode layer370_1may also be exposed. As illustrated in the drawing, the side surfaces of the electrode layer370_1are not entirely but are partially exposed so that a partial region thereof may contact the insulating film380_1. For example, the side surface of the electrode layer370_1may include the region contacting the insulating film380_1and the first exposed surface370S1that is exposed without the insulating film380_1formed thereon.

The insulating film380_1may include a first portion380S1and a second portion380S2. The insulating film380_1may be formed to expose the first exposed surface370S1of the electrode layer370_1, and the first portion380S1may be connected to the first exposed surface370S1and curved to have an inclined outer surface. For example, according to one embodiment, the thickness of the first portion380S1of the insulating film380_1may decrease in one direction in which the light emitting element300_1extends. The second portion380S2may be connected to the first portion380S1to form a flat outer surface. The first portion380S1may be disposed to surround a part of the electrode layer370_1and the second semiconductor layer320_1, and the second portion380S2may be disposed to surround an active layer330_1and a first semiconductor layer310_1. However, the present disclosure is not limited thereto, and the first portion380S1having the inclined outer surface may be disposed to surround a part of the active layer330_1.

In the light emitting element300_1according to the illustrated embodiment, the insulating film380_1may have portions having different thicknesses (e.g., the first portion380S1and the second portion380S2). As described above, the insulating film380_1may have a thickness of a certain level or more to protect at least the active layer330_1, and the second portion380S2of the insulating film380_1, which is the portion surrounding the active layer330_1, may have a thickness greater than that of the first portion380S1having the inclined outer surface.

According to one embodiment, in the insulating film380_1of the light emitting element300_1, a third thickness W3, that is, the thickness of the second portion380S2surrounding the active layer330_1, may be greater than the thickness of the first portion380S1having the inclined outer surface. Further, at the first portion380S1, a first thickness W1measured at the interface between the electrode layer370_1and the second semiconductor layer320_1and a second thickness W2measured at the interface between the second semiconductor layer320_1and the active layer330_1may be different from each other. Due to the inclined outer surface, the first thickness W1of the portion of the first portion380S1adjacent to the first exposed surface370S1of the electrode layer370_1that is exposed may be smaller than the second thickness W2of the portion adjacent to the second portion380S2, and the third thickness W3may be greater than the first thickness W1and the second thickness W2. In an embodiment, in the insulating film380_1, the third thickness W3of the second portion380S2may be within a range of about 60 nm to about 80 nm, and the first thickness W1and the second thickness W2of the first portion380S1having the inclined outer surface may be smaller than the third thickness W3. However, the present disclosure is not limited thereto.

Such a shape of the light emitting element300_1may be formed by concurrently (e.g., simultaneously) etching the upper surface of the insulating film380_1at the time of etching the insulating coating film3800during the manufacturing process of the light emitting element300_1.

FIG. 21is a cross-sectional view partially illustrating a manufacturing process of the light emitting element shown inFIG. 20.

Referring toFIG. 21, in the manufacturing process of the light emitting element300_1, the insulating coating film3800may be partially removed to expose the top surface of the electrode layer370_1. The process of partially removing the insulating coating film3800may be performed by a method of performing etching in a direction perpendicular to the lower substrate1000. At this time, the side surface of the insulating coating film3800may be partially etched. In the light emitting element300_1thus formed, the insulating film380_1may be etched to form the first portion380S1having the inclined outer surface.

As described above, the insulating film380_1of the light emitting element300_1may be partially etched and may have a reduced thickness during the manufacturing process of the display device10. In such an embodiment, the thickness relationship of the first thickness W1, the second thickness W2, and the third thickness W3of the insulating film380_1may be changed.

FIG. 22is a cross-sectional view illustrating a part of the display device including the light emitting element shown inFIG. 20.

FIG. 22illustrates a cross section passing through both ends of the light emitting element300_1of the display device10including the light emitting element300_1shown inFIG. 20. This embodiment is different from the embodiment shown inFIG. 7in that the light emitting element300is the light emitting element300_1shown inFIG. 20. For example, in the embodiment shown inFIG. 22, the insulating film380_1of the light emitting element300_1includes the first portion380S1having the inclined outer surface so that the shape of the first surface S1where the first contact electrode261and the insulating film380_1contact each other may be changed. In the following description, redundant descriptions will be omitted.

Referring toFIG. 22, the light emitting element300_1may have one side surface, that is, a lower surface, and the other side surface, that is, an upper surface, in a cross-sectional view. The one side surface may contact the second insulating layer520and the third insulating layer530. In the light emitting element300_1according to one embodiment, the insulating film380_1includes the first portion380S1forming the inclined outer surface, and the electrode layer370_1includes the second exposed surface370S2that is exposed. Accordingly, one side surface of the light emitting element300_1may be partially spaced apart from the second insulating layer520.

As illustrated in the drawing, on the one side surface of the light emitting element300_1, the first portion380S1of the insulating film380_1and the second exposed surface370S2of the electrode layer370_1may be spaced apart from the second insulating layer520.

The other side surface of the light emitting element300_1may contact the first contact electrode261, the third insulating layer530, and the second contact electrode262. On the other side surface, except the first surface S1contacting the first contact electrode261, the second surface S2contacting the second contact electrode262and the third surface S3contacting the third insulating layer530are substantially the same as those of the embodiment shown inFIG. 7. On the other hand, the first surface S1may be positioned across the first portion380S1forming the inclined outer surface of the insulating film380_1and the second exposed surface370S2of the electrode layer370_1that is exposed. For example, according to one embodiment, the first contact electrode261may contact the second exposed surface370S2of the electrode layer370_1and the first portion380S1of the insulating film380_1, and the first surface S1may be formed to be partially inclined or curved.

Further, as described above, the display device10may include the region in which the thickness of the insulating film380of the light emitting element300is partially different. The insulating film380_1may have a smaller thickness in the region corresponding to the first surface S1and the second surface S2than in the region corresponding to the third surface S3. In the light emitting element300_1shown inFIG. 20, the insulating film380_1may have the inclined outer surface at the first portion380S1, and the first thickness W1measured at the interface between the electrode layer370_1and the second semiconductor layer320_1may be smaller than the second thickness W2measured at the interface between the second semiconductor layer320_1and the active layer330_1.

During the manufacturing process of the display device10, the first portion380S1of the insulating film380_1may be partially etched so that a first thickness W1′ and a second thickness W2′ may be further reduced. On the other hand, in the insulating film380_1, the region where the third surface S3contacts the third insulating layer530may not be etched so that a third thickness W3′ measured in this region may be maintained at a constant level. For example, the third thickness W3′ may be greater than the first thickness W1′ and the second thickness W2′. Further, due to the inclined outer surface of the first portion380S1of the insulating film380_1of the light emitting element300_1, the first thickness W1′ may be smaller than the second thickness W2′.

Accordingly, the light emitting element300_1may have different diameters depending on positions. For example, in the light emitting element300_1, the first diameter Da, that is, the diameter measured in the other direction in the region corresponding to the third surface S3may be greater than the second diameter Db measured in the region corresponding to the second surface S2and the third diameter Dc measured in the region corresponding to the first surface S1. Further, in the light emitting element300_1, in the region corresponding to the first surface S1, the third-first diameter Dc1measured at the interface between the active layer330_1and the second semiconductor layer320_1may be greater than the third-second diameter Dc2measured at the interface between the second semiconductor layer320_1and the electrode layer370_1. However, the present disclosure is not limited thereto.

According to one embodiment, at the first portion380S1of the insulating film380_1, the first thickness W1′ and the second thickness W2′ may satisfy the following Equation (1):

where: θc is the inclination angle of the inclined outer surface of the insulating film380_1, W1′ is the thickness measured at the interface between the electrode layer370_1and the second semiconductor layer320_1in the insulating film380_1, W2′ is the thickness measured at the interface between the second semiconductor layer320_1and the active layer330_1in the insulating film380_1, and D is the thickness of the second semiconductor layer320_1.

As described above, the insulating film380_1of the light emitting element300_1has a thickness of a certain level or more to protect the active layer330_1and is disposed to surround at least the active layer330_1. The light emitting element300_1disposed in the display device10may be disposed to cover the active layer330_1and protect it even if the insulating film380_1is partially etched. As illustrated inFIG. 22, in the light emitting element300_1, the insulating film380_1may include the first portion380S1in which the inclined outer surface is formed, and the active layer330_1may be positioned to overlap the first portion380S1of the insulating film380_1.

To smoothly protect the active layer330_1, the first portion380S1may have a minimum thickness in the region overlapping the active layer330_1, and the inclination angle θc of the inclined outer surface may be defined. For example, the inclination angle θc of the first portion380S1may be measured with respect to the second semiconductor layer320_1so that the insulating film380_1may protect the active layer330_1. According to one embodiment, in the insulating film380_1of the light emitting element300_1of the display device10, the inclination angle θc of the first portion380S1may be about 70° or less, and the second thickness W2′ may be about 40 nm or more. The insulating film380_1of the light emitting element300_1may have the thickness within the above-described range and may have a thickness sufficient to protect the active layer330_1even when it is partially etched to form the first portion380S1having the inclined outer surface during the manufacturing process of the light emitting element300_1. For example, in the light emitting element300_1disposed in the display device10, the thickness (e.g., the second thickness W2′) of the insulating film380_1surrounding the active layer330_1is within the range of about 40 nm or more and the inclination angle θc is within the range of about 70° or less with respect to the second semiconductor layer320_1so that the light emitting element300_1may prevent damage of the active layer330_1. Accordingly, the display device10may include the light emitting element300_1and have improved luminous efficiency and luminous reliability.

In the insulating film380, the first thicknesses W1and W1′ measured at the interface between the second semiconductor layer320and the electrode layer370may be about 0 nm or more. For example, in the light emitting element300according to one embodiment, the insulating film380may not be disposed at the interface between the electrode layer370and the second semiconductor layer320.

FIG. 23is a schematic cross-sectional view of a light emitting element according to one embodiment, andFIG. 24is a cross-sectional view illustrating a part of the display device including the light emitting element ofFIG. 23.

Referring toFIG. 23, in a light emitting element300_2according to one embodiment, all side surfaces of an electrode layer370_2may be exposed and a side surface of a second semiconductor layer320_2may be partially exposed. Accordingly, the electrode layer370_2may include the first exposed surface370S1and the second exposed surface370S2, and the second semiconductor layer320_2may have an exposed surface32051. The insulating film380_2may include the first portion380S1connected to the exposed surface32051and having an inclined outer surface, and the second portion380S2connected to the first portion380S1and having a flat outer surface. The first portion380S1of the insulating film380_2may partially overlap only the second semiconductor layer320_2to partially expose the second semiconductor layer320_2. This embodiment is different from the embodiment shown inFIG. 20in that the side surface of the second semiconductor layer320_2is further exposed. In the insulating film380_2of the light emitting element300_2, the second thickness W2, that is, the thickness of the first portion380S1, may be smaller than the third thickness W3, that is, the thickness of the second portion380S2, and the thickness measured at the interface between the electrode layer370_2and the second semiconductor layer320_2at the first portion380S1may be about 0 nm. The other descriptions are the same as those described above with reference to the embodiment shown inFIG. 20and a detailed description thereof will be omitted.

Referring toFIG. 24, the light emitting element300_2may have one side surface, that is, a lower surface, and another side surface, that is, an upper surface, in a cross-sectional view. The one side surface may contact the second insulating layer520and the third insulating layer530. In the light emitting element300_2according to one embodiment, the electrode layer370_2may include the second exposed surface370S2that is exposed, and the second semiconductor layer320_2may include the exposed surface320S1that is partially exposed. Accordingly, one side surface of the light emitting element300_2may be partially spaced apart from the second insulating layer520. As illustrated in the drawing, on the one side surface of the light emitting element300_2, the first portion380S1of the insulating film380_2, the second exposed surface370S2of the electrode layer370_2, and the exposed surface320S1of the second semiconductor layer320_2may be spaced apart from the second insulating layer520.

The other side surface of the light emitting element300_2may contact the first contact electrode261, the third insulating layer530, and the second contact electrode262. The other side surface, except the first surface S1contacting the first contact electrode261, the second surface S2contacting the second contact electrode262, and the third surface S3contacting the third insulating layer530, is substantially the same as that of the embodiment shown inFIG. 20. On the other hand, the first surface S1may be positioned across the first portion380S1forming the inclined outer surface of the insulating film380_2, the second exposed surface370S2of the electrode layer370_2that is exposed, and the exposed surface320S1of the second semiconductor layer320_2that is exposed. For example, according to one embodiment, the first contact electrode261may contact the exposed surface320S1of the second semiconductor layer320_2, the second exposed surface370S2of the electrode layer370_2, and the first portion380S1of the insulating film380_2, and the first surface S1may be partially inclined or curved.

Further, in the light emitting element300_2shown inFIG. 23, the insulating film380_2has the inclined outer surface at the first portion380S1and the second semiconductor layer320_2is partially exposed so that the insulating film380_2is not disposed at the interface between the second semiconductor layer320_2and the electrode layer370_2, and the second thickness W2of the insulating film380_2may be defined at the interface between the second semiconductor layer320_2and the active layer330_2.

During the manufacturing process of the display device10, the first portion380S1of the insulating film380_2is partially etched so that the second thickness W2′ may be further reduced. On the other hand, in the insulating film380_2, the region where the third surface S3contacts the third insulating layer530is not etched so that the third thickness W3′, that is, the thickness measured in this region, may be maintained at a constant level. For example, the third thickness W3′ may be greater than the second thickness W2′. However, the second thickness W2′ may be within the range of at least about 40 nm in order to protect the active layer330_2of the light emitting element300_2. Accordingly, the light emitting element300_2may prevent damage of the active layer330_2, and the display device10may have improved luminous efficiency and luminous reliability.

According to some embodiments, the first electrode210and the second electrode220may not have the electrode stems210S and220S extending in the first direction DR1.

FIG. 25is a plan view illustrating one sub-pixel of a display device according to one embodiment.

Referring toFIG. 25, in a display device10_3, a first electrode210_3and a second electrode220_3may extend in one direction (e.g., in the second direction DR2). The first electrode210_3and the second electrode220_3may not have the electrode stems210S and220S extending in the first direction DR1. The display device10_3shown inFIG. 25is different from the display device10shown inFIG. 3in that the electrode stems210S and220S are omitted and one second electrode2203is further included. In the following description, redundant descriptions will be omitted.

As shown inFIG. 25, the plurality of first electrodes210_3and second electrodes220_3may extend in the second direction DR2in each sub-pixel PXn. The external bank430may also extend in the second direction DR2. The second electrode220_3and the external bank430may extend to another sub-pixel PXn adjacent in the second direction DR2. Accordingly, each of the sub-pixels PXn adjacent in the second direction DR2may receive the same electrical signal from the second electrode220_3.

Different from the display device10shown inFIG. 3, in the display device10_3shown inFIG. 25, the second electrode contact hole CNTS may be disposed in each second electrode220_3. The second electrode220_3may be electrically connected to the power electrode162of the circuit element layer PAL through the second electrode contact hole CNTS disposed in each sub-pixel PXn. Although the second electrode contact hole CNTS is illustrated as being formed in each of the two second electrodes220_3, the present disclosure is not limited thereto.

On the other hand, the first electrode210_3may extend in the second direction DR2to be terminated at the boundary of each sub-pixel PXn. Each of the sub-pixels PXn adjacent in the second direction DR2may include the first electrodes210_3spaced apart from each other, and they may receive different electrical signals through the first electrode contact holes CNTD. The first electrode210_3may have a shape extending in the second direction DR2and terminated at the boundary between adjacent sub-pixels PXn during the manufacturing process of the display device10. In the embodiment shown inFIG. 25, the light emitting elements300between one first electrode210_3and one second electrode220_3and the light emitting elements300between the other first electrode210_3and the other second electrode220_3may be connected in parallel.

In the display device10_3shown inFIG. 25, some electrodes210_3and220_3may disposed as floating electrodes without being electrically connected to the circuit element layer PAL through the electrode contact holes CNTD and CNTS. For example, from among the plurality of electrodes210_3and220_3, only the electrodes positioned at the outer part may receive the electrical signals through the electrode contact holes CNTD and CNTS, and the electrodes210_3and220_3disposed therebetween may not directly receive electrical signals. In such an embodiment, a part of the second electrodes220_3, (e.g., the second electrode220_3disposed between different first electrodes210_3) may extend in the second direction DR2and may be terminated at the boundary of each sub-pixel PXn without being disposed in another sub-pixel PXn, similar to the first electrode210_3. When some of the plurality of electrodes210_3and220_3are floating electrodes, the light emitting elements300disposed therebetween may be partially connected in series as well as in parallel. The external bank430may be disposed at the boundary of the sub-pixels PXn adjacent in the first direction DR1and may extend in the second direction DR2. The external bank430may be disposed at the boundary between the sub-pixels PXn adjacent in the second direction DR2and may extend in the first direction DR1. The description of the external bank430is the same as the above description with reference toFIG. 3. Further, the first contact electrode261_3and the second contact electrode262_3included in the display device10_3shown inFIG. 25are substantially the same as those of the display device10shown inFIG. 3.

FIG. 25illustrates that two first electrodes210_3and two second electrodes220_3are disposed and alternately spaced apart from each other. However, the present disclosure is not limited thereto, and some electrodes may be omitted or a greater number of electrodes may be disposed in the display device10_3.

The first electrode210and the second electrode220of the display device10may not necessarily have the shape extending in one direction. The shapes of the first electrode210and the second electrode220of the display device10may not be particularly limited as long as they are placed apart from each other to provide therebetween the space in which the light emitting elements300are disposed.

FIG. 26is a plan view illustrating one pixel of a display device according to one embodiment.

Referring toFIG. 26, at least some areas of a first electrode210_4and a second electrode220_4of a display device10_4according to an embodiment have curved shapes, and the curved area of the first electrode210_4may face the curved area of the second electrode220_4while being spaced apart from each other. The display device10_4shown inFIG. 26differs from the display device10shown in FIG.

2in that the shapes of the first and second electrodes210_4and220_4are different from those of the display device10. In the following description, redundant descriptions will be omitted.

The first electrode210_4of the display device10_4shown inFIG. 26may include multiple holes (e.g., multiple openings) HOL. For example, as illustrated in the drawing, the first electrode210_4may have a first hole HOL1, a second hole HOL2, and a third hole HOL3arranged in (e.g., adjacent in) the second direction DR2. However, the present disclosure is not limited to thereto, and the first electrode210_4may include a greater number of holes HOL, fewer holes HOL, or even a single hole HOL. Below, the description will be provided for an example where the first electrode210_4includes the first hole HOL1, the second hole HOL2, and the third hole HOL3.

In an embodiment, the first hole HOL1, the second hole HOL2, and the third hole HOL3may have a circular shape in a plan view. Accordingly, the first electrode210_4may have curved areas formed by the holes HOL and may face the second electrodes220_4in these curved areas. However, the present disclosure is not limited thereto. The first hole HOL1, the second hole HOL2, and the third hole HOL3are not particularly limited in shape as long as they can provide spaces for accommodating the second electrodes220_4therein. By way of example, the holes may have elliptical shapes, polygonal shapes, such as rectangles, or the like in a plan view.

The second electrode220_4may be plural in number, and the plurality of second electrodes220_4may be disposed in each sub-pixel PXn. By way of example, in each sub-pixel PXn, three second electrodes220_4may be disposed in each sub-pixel PXn corresponding to the first to third holes HOL1, HOL2, and HOL3of the first electrode210_4. The second electrodes220_4may be respectively disposed within the first to third holes HOL1, HOL2, and HOL3, surrounded by the first electrode210_4.

In an embodiment, the holes HOL of the first electrode210_4may have curved surfaces, and each second electrode220_4placed in the corresponding hole HOL of the first electrode210_4may also have a curved surface and be disposed to face the first electrode210_4with a gap therebetween. As illustrated inFIG. 26, the first electrode210_4may have the holes HOL having circular shapes in a plan view, and the second electrodes220_4may have circular shapes in a plan view. The curved surface of the area of the first electrode210_4where each hole HOL is formed may face the curved outer surface of the corresponding one of the second electrodes220_4with a gap therebetween. For example, the first electrode210_4may be disposed to surround (e.g., to extend around) the outer surfaces of the second electrodes220_4.

As stated above, light emitting elements300may be disposed between the first electrode210_4and the second electrode220_4. The display device10_4according to an embodiment may include the second electrode220_4having the circular shape and the first electrode210_4disposed to surround it, and the light emitting elements300may be arranged along the curved outer surface of the second electrode220_4. As stated above, because the light emitting elements300have the shapes extending in one direction, the light emitting elements300arranged along the curved outer surface of the second electrode220_4in each sub-pixel PXn may be disposed such that their extension directions are directed in different directions. Each sub-pixel PXn may have many different light emission directions depending on the directions in which the extension directions of the light emitting elements300are arranged. In the display device10_4according to an embodiment, by disposing the first and second electrodes210_4and220_4to have the curved shapes, the light emitting elements300disposed between them may be oriented toward different directions, and lateral visibility (e.g., viewing angle) of the display device10_4can be improved.

In concluding the detailed description, those skilled in the art will appreciate that many variations and modifications can be made to the embodiments described herein without substantially departing from the present disclosure. Therefore, the embodiments of the present disclosure described herein are to be used and understood in a generic and descriptive sense and not for purposes of limitation.