Patent Description:
In the case of conventional technology, GaN nanorod LEDs form point contact with electrodes when aligned in an interdigitated (IDT) pattern, which causes a poor current injection problem.

In addition, the conventional technology adopts a manner wherein, after fabricating nanorods, the fabricated nanorods are directly aligned and contacted through heat treatment or plating. Accordingly, an ohmic contact is not properly made to a p-GaN semiconductor layer, which causes decrease in current injection efficiency.

To address the problems, an n-GaN semiconductor layer and a p-GaN semiconductor layer are exposed by a photolithography process, and n-contact and p-contact are formed by an atomic layer deposition (ALD) method using deposition equipment with high coverage.

After the photolithography process, heat treatment (annealing) is performed at high temperature, and then a secondary photolithography process, etc. is required to carry out a process in which a conductor has an ohmic contact with the n-GaN semiconductor layer and the p-GaN semiconductor layer. Accordingly, there is a problem such as heat treatment at high temperature.

In addition, since the heat treatment is carried out at <NUM> or higher, printed circuit board (PCB) or glass is difficult to withstand a temperature of <NUM> or higher.

The thickness of InGaN/GaN epi are related to the thickness of n-GaN semiconductor layer, the thickness of a multi-quantum well structure layer and the thickness of p-GaN semiconductor layer.

Typically, the thickness of n-GaN semiconductor layer may be <NUM> to <NUM>, the thickness of a multi-quantum well structure layer may be <NUM> to <NUM> and the thickness of a p-GaN semiconductor layer may be <NUM> to <NUM>.

In the case of nanorods aligned by dielectrophoresis (DEP), a multi-quantum well structure layer may be located on an IDT pattern metal electrode. In this case, light does not emit due to electrical short.

In the case of the conventional technology, so as to prevent electrical short, it may be considered to fabricate an IDT pattern thinly so that the metal pattern does not come into contact with the multi-quantum well structure layer and does only come into contact with the p-GaN semiconductor layer. However, reducing a metal pattern to a sub-micron level is limited due to the limitations of photolithography in large displays. For example, a multi-quantum well structure layer includes an active layer.

As another method, it may be considered to make a p-GaN semiconductor layer long. In the case of the method, since the growth temperature of the p-GaN semiconductor layer is higher than the growth temperature of the multi-quantum well structure layer, the multi-quantum well structure layer is deteriorated when the p-GaN semiconductor layer is thickly grown so that efficiency is decreased.

Meanwhile, from the viewpoint of light emitting diode growth, there is an advantage that, as the thickness of thin film is reduced, stress applied to the multi-quantum well structure layer is relatively small and the growth time is reduced. Accordingly, it can be said that advantage increases as the length of nanorod is decreased.

However, electrical short may occur due to a thin p-GaN semiconductor layer.

Meanwhile, <FIG> and <FIG> illustrate a configuration according to the conventional technology wherein the vicinity of a p-GaN semiconductor layer and n-GaN semiconductor layer is exposed, and a conductor is deposited on a pattern so as to increase a coverage ratio for the exposed parts. In the case of such a conventional technology, a pattern material is limited due to high-temperature processing performed upon deposition after the formation of a nanorod LED.

<CIT> discloses a nano-scale LED element for a horizontal array assembly, a manufacturing method thereof, and a horizontal array assembly including the same.

<CIT> discloses a subminiature LED electrode assembly and a manufacturing method thereof. The subminiature LED electrode assembly comprises: a mounting electrode including a first mounting electrode and a second mounting electrode formed on the same plane and spaced apart from each other; an insulating film formed on exposed outer surfaces of the first mounting electrode and the second mounting electrode; subminiature LED elements arranged to have one end unit located at an upper part of the first mounting electrode and the other end unit located at an upper part of the second mounting electrode; a first driving electrode in contact with at least a part of one end unit of each of the subminiature LED elements; and a second driving electrode in contact with at least a part of the other end unit.

<CIT> discloses a light emitting device comprising: a substrate; a first electrode and a second electrode disposed and spaced apart from each other on the substrate; at least one light emitting diode disposed between the first electrode and the second electrode and having a first end and a second end on both sides in the longitudinal direction; an insulation pattern disposed to cover the top of the light emitting diode and exposing the first and second ends of the light emitting diode; a first contact electrode coming in contact with the first end of the light emitting diode and electrically connecting the first end to the first electrode; and a second contact electrode coming in contact with the second end of the light emitting diode and electrically connecting the second end to the second electrode. The insulation pattern completely covers the first and second ends of the light emitting diode when viewed from the top of the substrate, and has a cross-section with a decreasing width in the lower region.

Therefore, the present invention has been made in view of the above problems, and it is one object of the present invention to provide a GaN nanorod LED as well as a display comprising the nanorod LED. The object regarding the nanorod LED is solved by the features of independent claim <NUM>.

Further embodiments are defined in the respective dependent claims.

As the nanorod LED includes the conductor layer with various shapes and lengths, thereby it is capable of being efficiently aligned on various patterns and allowing current injection.

It is possible to prevent the occurrence of electrical short by thinly forming a first semiconductor layer so as to increase quantum efficiency while minimizing the stress of a multi-quantum well structure layer, and by forming a conductor layer on at least one of the first and second semiconductor layers while controlling the length and shape of the conductor layer.

It is possible to form an electrode contact having a relatively large area on first and second semiconductor layers by preferentially forming an ohmic contact layer and a conductor layer before separating the GaN nanorod LED from a substrate.

It is possible to omit a heat treatment process, performed at high temperature after aligning the nanorod LEDs on various patterns, by preferentially forming an ohmic contact layer and a conductor layer before separating the GaN nanorod LED from the substrate, thereby increasing a selection range of materials constituting a LED display.

It is possible to omit heat treatment accompanying an unnecessary photolithography process by previously forming an ohmic contact layer and a conductor layer before aligning the GaN nanorod LEDs on various patterns.

The present invention will now be described more fully with reference to the accompanying drawings, in which inter alia exemplary embodiments of the disclosure are shown.

In the description of embodiments of the present disclosure, certain detailed explanations of related known functions or constructions are omitted when it is deemed that they may unnecessarily obscure the essence of the disclosure.

In addition, the terms used in the specification are defined in consideration of functions used in the present disclosure, and can be changed according to the intent or conventionally used methods of clients, operators, and users. Accordingly, definitions of the terms should be understood on the basis of the entire description.

In the drawings, like reference numerals in the drawings denote like elements.

As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless context clearly indicates otherwise.

Expressions such as "A or B" and "at least one of A and/or B" should be understood to include all possible combinations of listed items.

Expressions such as "a first," "the first," "a second" and "the second" may qualify corresponding components irrespective of order or importance and may be only used to distinguish one component from another component without being limited to the corresponding components.

In the case in which a (e.g., first) component is referred as "(functionally or communicatively) connected" or "attached" to another (e.g., second) component, the first component may be directly connected to the second component or may be connected to the second component via another component (e.g., third component).

In the specification, the expression ". configured to. (or set to)" may be used interchangeably, for example, with expressions, such as ". suitable for. having ability to. modified to. manufactured to. enabling to. designed to. ," in the case of hardware or software depending upon situations.

In any situation, the expression "a device configured to. " may refer to a device configured to operate "with another device or component.

For examples, the expression "a processor configured (or set) to execute A, B, and C" may refer to a specific processor performing a corresponding operation (e.g., embedded processor), or a general-purpose processor (e.g., CPU or application processor) executing one or more software programs stored in a memory device to perform corresponding operations.

In addition, the expression "or" means "inclusive or" rather than "exclusive or".

That is, unless otherwise mentioned or clearly inferred from context, the expression "x uses a or b" means any one of natural inclusive permutations.

Hereinafter, the terms, such as 'unit' or 'module', etc., should be understood as a unit that processes at least one function or operation and that may be embodied in a hardware manner, a software manner, or a combination of the hardware manner and the software manner.

<FIG> illustrate a nanorod LED and a method of fabricating the same.

<FIG> sequentially illustrate the method of fabricating the nanorod LED.

More particularly, <FIG> illustrate forming a first conductor layer on a first semiconductor layer by the method of fabricating the nanorod LED, and <FIG> illustrate forming a second conductor layer on a second semiconductor layer after formation of the first conductor layer. Hereinafter, forming the second conductor layer after formation of the first conductor layer is described. However, the order of formation of the first conductor layer and the second conductor layer may be changed. In addition, only the first conductor layer may be formed, and the second conductor layer may not be formed.

Referring to <FIG>, the method of fabricating the nanorod LED includes sequentially forming a second semiconductor layer <NUM>, a multi-quantum well structure layer <NUM>; and forming a first deposition prevention layer <NUM> such that a first semiconductor layer <NUM> and a first ohmic contact layer <NUM> on a substrate <NUM> and such that second semiconductor layer <NUM> is partially covered.

By the method of fabricating the nanorod LED, an insulating material is coated on the first deposition prevention layer <NUM>, so that a passivation layer <NUM> is formed on the multi-quantum well structure layer <NUM>.

For example, the insulating material may include at least one of Al<NUM>O<NUM>, SiO<NUM>, and AlN.

For example, the passivation layer <NUM> may be made of at least one dielectric material selected from among Al<NUM>O<NUM>, SiO<NUM>, SiNx, SiONe, ZrO<NUM> and HfO<NUM> to form a dielectric layer.

For example, the first semiconductor layer <NUM> may be a gallium nitride (GaN) semiconductor layer (p-GaN) doped with a p-type impurity and may serve to supply holes.

For example, the second semiconductor layer <NUM> may be a gallium nitride (GaN) semiconductor layer (n-GaN) doped with an n-type impurity and may serve to supply electrons.

For example, the nanorod LED fabrication method includes forming the passivation layer <NUM> to physically passivate the multi-quantum well structure layer <NUM>.

Accordingly, the nanorod LED may prevent the occurrence of leakage current.

Referring to <FIG>, the method of fabricating the nanorod LED includes partially removing the passivation layer <NUM> formed on the first ohmic contact layer <NUM> by a method of etching an insulating film.

For example, the nanorod LED fabrication method may include etching the passivation layer <NUM> coated on the first ohmic contact layer <NUM>.

That is, by the nanorod LED fabrication method, a region on which a first conductor layer is to be formed is selectively etched.

For example, by the nanorod LED fabrication method, the first conductor layer may be formed on the first semiconductor layer <NUM> also when the first ohmic contact layer <NUM> is not formed.

Referring to <FIG>, the method of fabricating the nanorod LED includes additionally coating a second deposition prevention layer <NUM> on the first deposition prevention layer <NUM> to perform a conductor deposition process of forming the first conductor layer.

For example, the nanorod LED fabrication method includes forming the second deposition prevention layer <NUM>, which is related to conductor deposition, on the first deposition prevention layer <NUM>.

Referring to <FIG>, the method of fabricating the nanorod LED includes depositing a conductor on the first ohmic contact layer <NUM> to form a first conductor layer <NUM> with various shapes.

For example, according to embodiments of the present invention, the first conductor layer <NUM> may be formed in any one shape of a shape inclined to one side, and a zigzag shape. Specific shapes of the first conductor layer <NUM> are more particularly described with reference to <FIG>.

For example, when the first ohmic contact layer <NUM> is not formed, the first conductor layer <NUM> may be formed in any one shape of a shape parallel to the first semiconductor layer <NUM> and a zigzag shape.

For example, the parallel shape refers to a shape wherein the first conductor layer <NUM> is formed parallel to the first semiconductor layer <NUM>. Here, the first conductor layer <NUM> may be formed on the entire upper surface of the first semiconductor layer <NUM> or on a portion of a surface thereof.

For example, the nanorod LED fabrication method includes performing an annealing process of forming the first conductor layer <NUM> after depositing a conductor on the first ohmic contact layer <NUM>.

In addition, the nanorod LED fabrication method includes removing the first deposition prevention layer <NUM> and the second deposition prevention layer <NUM> before the annealing process after completing the conductor deposition process of forming the first conductor layer <NUM>.

For example, the first deposition prevention layer <NUM> and the second deposition prevention layer <NUM> may be layers that prevent the deposition of Spin on Glass (SOG), resin, and the like and are easily removed.

The method of fabricating the nanorod LED includes physically passivating the multi-quantum well structure layer <NUM> before separating the nanorod from the substrate to prevent current leakage.

In addition, by the nanorod LED fabrication method, an ohmic contact is preferentially performed on the first semiconductor layer <NUM>, and a deposition process, such as an atomic layer deposition (ALD), performed after separating and aligning the nanorod LED from the substrate is not additionally required.

In addition, since high temperature is not required in an annealing process, higher current injection efficiency may be expected.

In other words, by the nanorod LED fabrication method, the process of forming the first ohmic contact layer <NUM> and the first conductor layer <NUM> on the first semiconductor layer <NUM> is preferentially performed, and the nanorod LED is separated and aligned from the substrate later, so that an additional deposition process may not be required.

By the nanorod LED fabrication method, the length and shape of the first conductor layer <NUM> are controlled such that the multi-quantum well structure layer <NUM> is disposed between two electrodes of the electrode pattern when the conductor layer of the nanorod LED is aligned on the electrode pattern.

In other words, by the nanorod LED fabrication method, the length and shape of the first conductor layer <NUM> are controlled on the first semiconductor layer <NUM> or the first ohmic contact layer <NUM> such that the multi-quantum well structure layer <NUM> is disposed within the width of an unpatterned region.

Accordingly, the conductor layer of the present disclosure may be formed on at least one of the first and second semiconductor layers while minimizing the stress of the multi-quantum well structure layer, thinly forming the first semiconductor layer to increase quantum efficiency, and controlling the length and shape of the conductor layer, thereby preventing the occurrence of electrical short.

Referring to <FIG>, the method of fabricating the nanorod LED includes placing a receptor <NUM> on the first conductor layer <NUM> to form a second ohmic contact layer and second conductor layer also on the second semiconductor layer <NUM>.

Referring to <FIG>, the method of fabricating the nanorod LED includes lifting-off the substrate <NUM> using the receptor <NUM>.

In addition, the nanorod LED fabrication method includes etching the second semiconductor layer <NUM> such that an upper part of the second semiconductor layer <NUM> is exposed.

The nanorod LED fabrication method may include forming a second ohmic contact layer <NUM> on the second semiconductor layer <NUM>.

Referring to <FIG>, the nanorod LED fabrication method may include forming a third deposition prevention layer <NUM> on the remaining region except for a region, on which a second conductor layer <NUM> is to be formed, of the second ohmic contact layer <NUM>, in accordance with an embodiment of the present disclosure.

Referring to <FIG>, the method of fabricating the nanorod LED includes depositing a conductor on the second semiconductor layer <NUM> to form a second conductor layer <NUM> with various shapes.

For example, the second conductor layer <NUM> may be formed in any one shape of a shape inclined to one side, a shape parallel to the second ohmic contact layer <NUM>, and a zigzag shape. A specific shape thereof is more particularly described below with reference to <FIG>.

In accordance with an embodiment of the present disclosure, the nanorod LED fabrication method includes depositing the second conductor layer <NUM> on the second semiconductor layer <NUM> when the second ohmic contact layer <NUM> is not formed.

Meanwhile, the length and shape of the second conductor layer <NUM> may be controlled to be disposed between two electrodes of the pattern of the multi-quantum well structure layer <NUM>.

For example, the nanorod LED fabrication method includes performing an annealing process of forming the second conductor layer <NUM> after depositing a conductor on the second ohmic contact layer <NUM>.

In addition, the nanorod LED fabrication method includes removing the third deposition prevention layer <NUM> before the annealing process after completing the conductor deposition process of forming the second conductor layer <NUM>.

The nanorod LED fabrication method may provide a nanorod LED including the first conductor layer <NUM> and second conductor layer <NUM> that are respectively formed on opposite sides of the first semiconductor layer <NUM> and the second semiconductor layer <NUM>.

The nanorod LED may include a passivation layer <NUM> that is formed on opposite sides of the first semiconductor layer <NUM>, the multi-quantum well structure layer <NUM>, the second semiconductor layer <NUM>, the first semiconductor layer <NUM>, the multi-quantum well structure layer <NUM>, and the second semiconductor layer <NUM>.

For example, the multi-quantum well structure layer <NUM> may also be referred to as a multiple quantum well (MQW) layer or an active layer.

In addition, the first conductor layer <NUM> is formed, in any one shape of a shape inclined to one side, or a zigzag shape, on the first semiconductor layer <NUM> of the nanorod LED.

In addition, after the first conductor layer <NUM> is formed on the first semiconductor layer <NUM>, the second conductor layer <NUM> may be formed, in any one shape of a shape inclined to one side, a shape parallel to the second semiconductor layer <NUM> and a zigzag shape, on the second semiconductor layer <NUM> of the nanorod LED.

For example, when the first ohmic contact layer <NUM> is formed on the first semiconductor layer <NUM> of the nanorod LED, the first conductor layer <NUM> is formed on the first ohmic contact layer <NUM>.

For example, when the second ohmic contact layer <NUM> is formed on the second semiconductor layer <NUM> of the nanorod LED, the second conductor layer <NUM> is formed on the second ohmic contact layer <NUM>.

In accordance with an embodiment of the present disclosure, the second semiconductor layer <NUM>, the multi-quantum well structure layer <NUM> and the first semiconductor layer <NUM> of the nanorod LED are sequentially formed with respect to the substrate to form a vertical structure.

The nanorod LED may be formed on a first substrate for forming the nanorod LED, and then may be aligned on a second substrate which is to be separated from the first substrate and into which a pattern is to be inserted.

The first and second conductor layers <NUM> and <NUM> may be formed of at least one conductive material of indium tin oxide (ITO) and metal materials.

In addition, the first and second conductor layers <NUM> and <NUM> may be deposited by at least one of an electroplating method, a sputtering method and a thermal evaporation method.

For example, the first semiconductor layer <NUM> is a p-type impurity-doped gallium nitride (GaN) semiconductor layer (p-GaN) and serves to supply holes, and the second semiconductor layer <NUM> is an n-type impurity-doped gallium nitride (GaN) semiconductor layer (n-GaN) and serves to supply electrons.

For example, the multi-quantum well structure layer <NUM> may be composed of a quantum barrier layer, an active layer, and the like.

Accordingly, the GaN nanorod LEDs are aligned on various patterns with two electrodes by forming a conductor layer with various shapes on the GaN nanorod LED, and may efficiently inject current thereto.

In addition, an ohmic contact layer and a conductor layer may be preferentially formed before separating the GaN nanorod LED from the substrate, thereby forming an electrode contact with a relatively large area on the first and second semiconductor layers.

In the above description, it was exemplified that the first ohmic contact layer and the first conductor layer are formed on the first semiconductor layer, the length and shape of the first conductor layer are controlled such that, when aligned on various patterns with two electrodes, the active layer is disposed between two electrodes of the electrode pattern, and additionally the length and shape of the second conductor layer are controlled such that the active layer is disposed between two electrodes of the electrode pattern upon aligning on various electrode patterns also when the second ohmic contact layer and the second conductor layer are formed on the second semiconductor layer.

The first ohmic contact layer and the second ohmic contact layer may be selectively formed, and the first conductor layer and the second conductor layer may also be selectively formed.

In the following disclosure, a structure composed of a first ohmic contact layer and a second ohmic contact layer is described, but the first ohmic contact layer and the second ohmic contact layer may be selectively formed.

<FIG> illustrate forming a first conductor layer of a nanorod LED according to an embodiment of the present disclosure.

<FIG> illustrates an embodiment of the present invention in which a first conductor layer formed by depositing a conductor in a state in which a nanorod LED fabrication sample is inclined.

Referring to <FIG>, the nanorod LED according to an embodiment of the present invention includes a substrate <NUM> and a second semiconductor layer <NUM>, multi-quantum well structure layer <NUM>, first semiconductor layer <NUM>, first ohmic contact layer <NUM>, passivation layer <NUM> and first conductor layer <NUM> formed on the substrate <NUM>.

In accordance with the embodiment of the present disclosure, the first conductor layer <NUM> may have a shape inclined to one side.

For example, by the nanorod LED fabrication method, a first conductor layer <NUM> having a shape inclined to one side may be formed by depositing a conductor thicker than a reference in a state in which a nanorod LED fabrication sample is inclined to one side.

For example, the thickness of the first conductor layer <NUM> may be controlled using an electroplating method. For example, the thickness of the first conductor layer <NUM> may be related to the length of the first conductor layer <NUM>, and, as the thickness of the first conductor layer <NUM> increases, the length of the first conductor layer <NUM> also increases.

<FIG> illustrates depositing a conductor while rotating a nanorod LED fabrication sample at a constant speed, thereby forming the first conductor layer of the nanorod LED.

Referring to <FIG>, the nanorod LED includes a substrate <NUM> and a second semiconductor layer <NUM>, multi-quantum well structure layer <NUM>, first semiconductor layer <NUM>, first ohmic contact layer <NUM>, passivation layer <NUM> and first conductor layer <NUM> formed on the substrate <NUM>.

The first conductor layer <NUM> may have a thin thickness and may have a shape of covering the entire upper surface of the first ohmic contact layer <NUM>.

For example, when the first ohmic contact layer <NUM> is not formed, the first conductor layer <NUM> may be formed to cover the entire upper surface of the first semiconductor layer <NUM>.

For example, the nanorod LED fabrication method includes depositing a conductor thinner than a reference in a state in which a nanorod LED fabrication sample rotates, thereby forming the first conductor layer <NUM> having a shape parallel to the first ohmic contact layer <NUM>.

<FIG> illustrates an embodiment of thickly depositing a conductor in a state, in which a nanorod LED fabrication sample rotates, to form the first conductor layer of the nanorod LED according to an embodiment of the present invention.

Referring to <FIG>, the nanorod LED according to the embodiment of the present disclosure includes a substrate <NUM>, and a second semiconductor layer <NUM>, multi-quantum well structure layer <NUM>, first semiconductor layer <NUM>, first ohmic contact layer <NUM>, passivation layer <NUM> and first conductor layer <NUM> formed on the substrate <NUM>.

In accordance with the embodiment of the present invention, the first conductor layer <NUM> has a zigzag shape.

For example, the nanorod LED fabrication method may include depositing a conductor thicker than a reference in a state, in which a nanorod LED fabrication sample rotates, to form the first conductor layer <NUM> having a zigzag shape.

In accordance with the embodiment of the present disclosure, since the criterion for depositing the conductor is related to the degree of covering an upper part of the first semiconductor layer, the thicknesses of the first conductor layers respectively illustrated in <FIG> and <FIG> are larger than a reference, and the thickness of the first conductor layer illustrated in <FIG> is smaller than the reference, the reference may be a value between the thicknesses of the first conductor layers <NUM> and <NUM> and the thickness of the first conductor layer <NUM>.

In addition, the thickness of the first conductor layer is correlated with the deposition time of the conductor.

<FIG> illustrate forming a second conductor layer of a nanorod LED according to an embodiment of the present disclosure.

<FIG> illustrates an embodiment of a second conductor layer formed by depositing a conductor in a state in which a nanorod LED fabrication sample is inclined.

Referring to <FIG>, the nanorod LED according to an embodiment of the present invention includes a receptor <NUM>, and a first conductor layer <NUM>, first semiconductor layer <NUM>, multi-quantum well structure layer <NUM>, passivation layer <NUM>, second semiconductor layer <NUM>, second ohmic contact layer <NUM> and second conductor layer <NUM> formed on the receptor <NUM>.

In accordance with the embodiment of the present invention, the second conductor layer <NUM> has a shape inclined to one side.

For example, by the nanorod LED fabrication method, a second conductor layer <NUM> having a shape inclined to one side may be formed by depositing a conductor thicker than a reference in a state in which a nanorod LED fabrication sample is inclined to one side.

For example, the thickness of the second conductor layer <NUM> may be controlled using an electroplating method.

<FIG> illustrates depositing a conductor while rotating a nanorod LED fabrication sample at a constant speed, thereby forming the second conductor layer of the nanorod LED.

Referring to <FIG>, the nanorod LED includes a receptor <NUM>, and a first conductor layer <NUM>, first semiconductor layer <NUM>, multi-quantum well structure layer <NUM>, passivation layer <NUM>, second semiconductor layer <NUM>, second ohmic contact layer <NUM> and second conductor layer <NUM> formed on the receptor <NUM>.

The second conductor layer <NUM> may have a thin thickness and may have a shape of covering the entire upper surface of the second semiconductor layer <NUM>.

For example, the nanorod LED fabrication method includes depositing a conductor thinner than a reference in a state in which a nanorod LED fabrication sample rotates, thereby forming the second conductor layer <NUM> having a shape parallel to the second ohmic contact layer <NUM>.

<FIG> illustrates an embodiment of thickly depositing a conductor in a state, in which a nanorod LED fabrication sample rotates, to form the second conductor layer of the nanorod LED according to an embodiment of the present invention.

Referring to <FIG>, the nanorod LED according to the embodiment of the present disclosure includes a receptor <NUM>, and a first conductor layer <NUM>, first semiconductor layer <NUM>, multi-quantum well structure layer <NUM>, passivation layer <NUM>, second semiconductor layer <NUM>, second ohmic contact layer <NUM> and second conductor layer <NUM> formed on the receptor <NUM>.

In accordance with the embodiment of the present invention, the second conductor layer <NUM> has a zigzag shape.

For example, the nanorod LED fabrication method may include depositing a conductor thicker than a reference in a state, in which a nanorod LED fabrication sample rotates, to form a second conductor layer <NUM> having the zigzag shape.

In accordance with the embodiment of the present disclosure, since the criterion for depositing the conductor is related to the degree of covering an upper part of the second ohmic contact layer, the thicknesses of the second conductor layers respectively illustrated in <FIG> and <FIG> are larger than a reference, and the thickness of the second conductor layer illustrated in <FIG> is smaller than the reference, the reference may be a value between the thicknesses of the second conductor layers <NUM> and <NUM> and the thickness of the second conductor layer <NUM>.

In addition, the thickness of the second conductor layer is correlated with the deposition time of the conductor.

The nanorod LED may include a conductor layer formed on at least one of the first and the second semiconductor layers.

In other words, the nanorod LED may include a conductor layer selectively formed on any one of the first and second semiconductor layers.

For example, the first conductor layer may be formed on the first semiconductor layer of the nanorod LED, or a second conductor layer may be formed on the second semiconductor layer of the nanorod LED.

In other words, the nanorod LED may be formed in a structure of including both the first conductor layer and the second conductor layer, a structure of including only the first conductor layer, or a structure of including only the second conductor layer.

<FIG> illustrate forming a transparent electrode of a nanorod LED.

<FIG> illustrate depositing an insulating film and, after exposing an upper part of a first ohmic contact layer, directly depositing a transparent electrode on a first semiconductor layer, without secondary deposition prevention layer coating.

Referring to <FIG>, the method of fabricating the nanorod LED includes forming a second semiconductor layer <NUM>, a multi-quantum well structure layer <NUM> and a first semiconductor layer <NUM> on a substrate <NUM>, forming a passivation layer <NUM> to passivate the multi-quantum well structure layer <NUM>, and partially removing the passivation layer <NUM>, formed on an upper part of the first semiconductor layer <NUM>, using a method of etching an insulating film.

Here, a first ohmic contact layer <NUM> may be formed on the first semiconductor layer <NUM>.

That is, the passivation layer <NUM> may be formed after the second semiconductor layer <NUM>, the multi-quantum well structure layer <NUM> and the first semiconductor layer <NUM> are sequentially formed, and then the first ohmic contact layer <NUM> is formed, and then the deposition prevention layer <NUM> is formed.

For example, the nanorod LED fabrication method may include etching the passivation layer <NUM> coated on the first semiconductor layer <NUM>.

That is, by the nanorod LED fabrication method, a region in which a transparent electrode is to be formed is selectively etched.

Referring to <FIG>, the method of fabricating the nanorod LED according to an embodiment of the present disclosure includes coating a transparent electrode-forming material on the deposition prevention layer <NUM>.

For example, the transparent electrode-forming material may include a metal material such as ZnO, AZO and ITO.

For example, the passivation layer <NUM> mutually passivates the transparent electrode, the second semiconductor layer <NUM> and the multi-quantum well structure layer <NUM>.

Referring to <FIG>, the method of fabricating the nanorod LED may include removing the deposition prevention layer <NUM>, and performing heat treatment in a state in which the transparent electrode-forming material is coated on the first ohmic contact layer <NUM> to form a transparent electrode <NUM>.

<FIG> illustrates controlling the thickness of a conductor layer of a nanorod LED using electroplating.

Referring to <FIG>, the nanorod LED fabrication method includes laminating a seed layer <NUM> for electroplating on a first ohmic contact layer <NUM> in a state in which a second semiconductor layer <NUM>, a multi-quantum well structure layer <NUM>, a first semiconductor layer <NUM> and a first ohmic contact layer <NUM> are formed on a substrate <NUM>.

For example, the seed layer <NUM> is formed on the first ohmic contact layer <NUM> before dry etching for forming a nanorod LED to form the seed layer <NUM>, so that the thickness of the seed layer <NUM> may be controlled through electroplating after forming a nanorod LED in a subsequent process.

Meanwhile, a deposition prevention layer <NUM> for forming a passivation layer may be formed after forming the metal layer <NUM>.

The seed layer <NUM> on the left and the seed layer <NUM> on the right illustrate an increase in the thickness of the seed layer through electroplating.

For example, the seed layer <NUM>, whose thickness is controlled through electroplating, may be referred to as a metal head and may also be referred to as an electroplated seed layer.

That is, the nanorod LED fabrication method may include sequentially forming an ohmic contact material and a seed layer for electroplating on the first semiconductor layer, and then thickly forming a conductor layer using electroplating after forming a nanorod LED in a subsequent process.

Accordingly, by the nanorod LED fabrication method, the length (thickness) of the conductor layer may be controlled using electroplating.

<FIG> illustrates a display in which nanorod LEDs according to an embodiment of the present disclosure are aligned.

<FIG> exemplifies a display including plurality of nanorod LEDs aligned on an interdigitated (IDT) pattern that includes first and second electrodes.

Referring to <FIG>, a display <NUM> according to a conventional technology includes a first electrode <NUM> and a second electrode <NUM>. Here, a plurality of nanorod LEDs <NUM> are aligned between the first electrode <NUM> and the second electrode <NUM>.

Meanwhile, a display <NUM> according to an embodiment of the present disclosure includes a first electrode <NUM> and a second electrode <NUM>. Here, a plurality of nanorod LEDs <NUM> are aligned between the first electrode <NUM> and the second electrode <NUM>.

The display <NUM> according to a conventional technology requires an additional process of forming an ohmic contact layer or a conductor layer because an ohmic contact layer or a conductor layer is not separately formed on the nanorod LEDs <NUM>.

Meanwhile, in the case of the display <NUM> according to the embodiment of the present disclosure, an ohmic contact layer and a conductor layer are previously formed at sites of the nanorod LEDs <NUM> in contact with the first electrode <NUM> or the second electrode <NUM>.

In accordance with the embodiment of the present disclosure, the nanorod LEDs <NUM> includes a first semiconductor layer, a multi-quantum well structure layer, a second semiconductor layer and a passivation layer formed on opposite side surfaces of the first semiconductor layer, the multi-quantum well structure layer and the second semiconductor layer.

In the nanorod LEDs <NUM> according to the embodiment of the present disclosure, the first conductor layer may be formed on the first semiconductor layer in any one shape of a shape inclined to one side from the top of the first semiconductor layer or the first ohmic contact layer, or a zigzag shape.

In the nanorod LEDs <NUM> according to an embodiment of the present disclosure, the second conductor layer may be formed on the second semiconductor layer in any one shape of a shape inclined to one side from an upper part of the second semiconductor layer or the second ohmic contact layer, a shape parallel to the second semiconductor layer or the second ohmic contact layer and a zigzag shape.

Meanwhile, in the nanorod LEDs <NUM>, the first conductor layer may be formed on the first semiconductor layer or the first ohmic contact layer, or the first and second conductor layers may be respectively formed on the first and second semiconductor layers or the first and second ohmic contact layers.

The first semiconductor layer may be a p-type impurity-doped gallium nitride (GaN) semiconductor layer (p-GaN) and may serve to supply holes, and the second semiconductor layer may be an n-type impurity-doped gallium nitride (GaN) semiconductor layer (n-GaN) and may serve to supply electrons.

For example, the first electrode may contact the first conductor layer, and the second electrode may contact the second conductor layer.

Accordingly, preferentially forming an ohmic contact layer and a conductor layer may be included before separating the GaN nanorod LED from the substrate, so that heat treatment at high temperature performed after aligning nanorods to an IDT pattern may be omitted. Accordingly, a selection range of materials constituting a light emitting diode (LED) display increases.

In addition, by the present invention, heat treatment due to unnecessary photolithography may be omitted because an ohmic contact layer is previously formed before aligning GaN nanorod LEDs to an IDT pattern.

Meanwhile, the length and shape of each of the first and second conductor layers may be controlled such that the active layer of the nanorod LED is disposed between the first electrode <NUM> and the second electrode <NUM>.

Controlling the length and shape of the first conductor layer between the first electrode and the second electrode according to the method of fabricating the nanorod LED is more particularly described with reference to <FIG>.

<FIG> illustrates controlling the length of a conductor layer of a nanorod LED.

Referring to <FIG>, the nanorod LED is disposed between a first electrode <NUM> and second electrode <NUM> of a pattern. Here, the lengths of a conductor layer <NUM>, a conductor layer <NUM> and a conductor layer <NUM> may be controlled such that a multi-quantum well structure layer <NUM>, a multi-quantum well structure layer <NUM> and a multi-quantum well structure layer <NUM> can be located in a width <NUM> between the first electrode <NUM> and the second electrode <NUM>.

Although the conductor layer <NUM>, the conductor layer <NUM> and the conductor layer <NUM> have different lengths, all of the multi-quantum well structure layer <NUM>, the multi-quantum well structure layer <NUM> and the multi-quantum well structure layer <NUM> are located in the width <NUM>.

A first semiconductor layer of the nanorod LED is formed in an epi level to minimize the stress of a multi-quantum well structure layer and increase quantum efficiency.

When the thickness of the first semiconductor layer is formed in an epi level, electrical short may occur. Accordingly, it may be necessary to control the length of the conductor layer such that the multi-quantum well structure layer can be located in the width <NUM>.

Accordingly, the method of fabricating the nanorod LED may include controlling the thickness (length) of the conductor layer after forming the ohmic contact layer so that the multi-quantum well structure layer can be located in the width <NUM>.

The method of fabricating the nanorod LED may include thickly forming the conductor layer on the ohmic contact layer so that the multi-quantum well structure layer can be disposed at the center between two electrodes of the IDT pattern.

In the method of fabricating the nanorod LED, the conductor formed on the first semiconductor layer may be made of any material with conductivity including metal and ITO.

Since a junction of a conductor layer formed according to the method corresponds to a junction between an IDT pattern and a metal, a junction with low electrical resistance may be formed.

The nanorod LED may be aligned on various patterns without being limited to an IDT pattern. As one example of various patterns, a circle pattern is exemplified and described with reference to <FIG>.

<FIG> illustrates a plurality of nanorod LEDs aligned on a circle pattern according to an embodiment of the present invention.

Referring to <FIG>, the nanorod LEDs according to the embodiment of the present invention may be aligned on a circle pattern <NUM>.

For example, the circle pattern <NUM> includes a second electrode <NUM> and a first electrode <NUM>, and a plurality of nanorod LEDs <NUM> are aligned between the second electrode <NUM> and the first electrode <NUM>.

In the nanorod LEDs <NUM>, a conductor layer may be formed in a portion in contact with the first electrode <NUM>, and the length and shape of the conductor layer may be controlled such that a multi-quantum well structure layer of each of the nanorod LEDs <NUM> is located between the second electrode <NUM> and the first electrode <NUM>.

<FIG> and <FIG> illustrate a method of aligning a nanorod on an IDT pattern according to a conventional technology.

<FIG> illustrates a process of aligning a nanorod LED on an IDT pattern according to a conventional technology.

Referring to <FIG>, in step S901, a nanorod LED <NUM> is aligned on an IDT pattern <NUM>, and then, after a deposition prevention layer, a conductor <NUM> is deposited.

In step S902, heat treatment fixation is performed such that the nanorod LED <NUM> is in contact with the conductor <NUM> on the IDT pattern <NUM>.

In other words, in the case of a manner of aligning a nanorod LED on an IDT pattern according to a conventional technology, the vicinity of a p-GaN semiconductor layer and an n-GaN semiconductor layer is exposed by a deposition prevention process to fix the nanorod LED after aligning the nanorod LED. To increase coverage for the exposed portions, a conductor is deposited again using ALD.

As a subsequent process, heat treatment should be performed. However, it is difficult to thermally treat PCB or glass at <NUM> or higher. Accordingly, there is a limit in applying a pattern material.

<FIG> illustrates a structure formed according to the method of aligning a nanorod LED on an IDT pattern shown in <FIG>.

Referring to <FIG>, a display <NUM> has a structure wherein a plurality of nanorod LEDs <NUM> are aligned between the first electrode <NUM> and the second electrode <NUM>, and a conductor layer <NUM> is formed on opposite side surfaces of each of the LEDs <NUM>.

As described above with reference to <FIG>, additional heat treatment is required to form the conductor layer <NUM>, but it is difficult to thermally treat PCB or glass at <NUM> or higher.

Accordingly, there is a limit in applying a pattern material.

As apparent from the above description, the present invention provides a GaN nanorod LED including a conductor layer with various shapes and lengths, thereby being capable of being efficiently aligned on various patterns and allowing current injection.

The present invention can prevent the occurrence of electrical short by thinly forming a first semiconductor layer so as to increase quantum efficiency while minimizing the stress of a multi-quantum well structure layer, and by forming a conductor layer on at least one of the first and second semiconductor layers while controlling the length and shape of the conductor layer.

The present invention can form an electrode contact having a relatively large area on first and second semiconductor layers by preferentially forming an ohmic contact layer and a conductor layer before separating a GaN nanorod LED from a substrate.

The present invention can omit a heat treatment process, performed at high temperature after aligning nanorods on various patterns, by preferentially forming an ohmic contact layer and a conductor layer before separating a GaN nanorod LED from a substrate, thereby increasing a selection range of materials constituting a light emitting diode (LED) display.

The present invention can omit heat treatment accompanying an unnecessary photolithography process by previously forming an ohmic contact layer and a conductor layer before aligning GaN nanorod LEDs on various patterns.

In the aforementioned embodiments, constituents of the present invention were expressed in a singular or plural form depending upon embodiments thereof.

However, the singular or plural expressions should be understood to be suitably selected depending upon a suggested situation for convenience of description, and the aforementioned embodiments should be understood not to be limited to the disclosed singular or plural forms. In other words, it should be understood that plural constituents may be a singular constituent, or a singular constituent may be plural constituents.

Claim 1:
A nanorod light emitting diode, LED, the nanorod LED comprising:
a first semiconductor layer (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>);
a multi-quantum well structure layer (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>);
a second semiconductor layer (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>);
a first conductor layer (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>) formed on the first semiconductor layer and a second conductor layer (<NUM>; <NUM>; <NUM>; <NUM>) formed on the second semiconductor layer
a passivation layer (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>; <NUM>) formed on opposite side surfaces of the first semiconductor layer, the multi-quantum well structure layer and the second semiconductor layer;
wherein a length and shape at least one of the first conductor layer and the second conductor layer are controlled such that the multi-quantum well structure layer can be disposed between two electrodes (<NUM>, <NUM>; <NUM>, <NUM>; <NUM>, <NUM>; <NUM>, <NUM>; <NUM>, <NUM>) of an electrode pattern on which the first and second conductor layers are to be aligned,
characterised by
a first ohmic contact layer (<NUM>; <NUM>; <NUM>; <NUM>) formed between the first semiconductor layer and the first conductor layer;
a second ohmic contact layer (<NUM>; <NUM>; <NUM>; <NUM>) formed between the second semiconductor layer and the second conductor layer; and in that
at least one of the first conductor layer and the second conductor layer is formed with
a shape inclined to one side or with a zigzag shape on the at least one semiconductor layer.