Light-emitting device and method for manufacturing the same

The embodiment is to provide a light emitting device and a method for manufacturing the same, in which the light emitting device includes a first conductive semiconductor layer; an active layer formed on the first conductive semiconductor layer; a second conductive semiconductor layer formed on the active layer; and a phosphor layer formed on the second conductive semiconductor layer; in which the phosphor layer includes a phosphor receiving member including a plurality of cavities and phosphor particles fixed in the cavities.

The present application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2009-0109369, filed on Nov. 12, 2009, the entirety of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The embodiment relates to a light emitting device and a method for manufacturing the same.

2. Description of the Related Art

A light-emitting device (LED) is a semiconductor light-emitting device that transforms current into a light. Recently, the use of the light-emitting device has been increasing as a source of light for display, a source of light for automobile and a source of light for lighting due to gradually increasing of a luminance of LED.

Recently, a high power light-emitting chip available for implementing full colors by producing a short wavelength light, such as blue or green has been developed. To this end, the light-emitting diode having various colors can be effective in combinations, and a light-emitting diode emitting a white light can be implemented by absorbing a part of light outputted from the light-emitting chip and applying a phosphor outputting different wavelengths with the wavelengths of light on the light-emitting chip.

SUMMARY OF THE INVENTION

The embodiment is to provide a light-emitting device and a method for manufacturing the same that can easily and precisely control a distribution position and distribution degree of a phosphor on the light-emitting device and prevents a waste of the phosphor materials upon processing.

According to one aspect of the embodiment, there is provided a light-emitting device and a method for manufacturing the same that can improve light efficiency on a surface of the light-emitting device chip, and can remove air layer obstructing a total reflection.

A light-emitting device according to an exemplary embodiment of the present invention includes: a first conductive semiconductor layer; an active layer formed on the first conductive semiconductor layer; a second conductive semiconductor layer formed on the active layer; and a phosphor layer formed on the second conductive semiconductor layer, in which the phosphor layer includes a phosphor receiving member having a plurality of cavities and phosphor particles fixed in the cavities.

A method for manufacturing the light-emitting device according to another exemplary embodiment of the present invention includes: forming the first conductive semiconductor layer on the substrate; forming the active layer on the first conductive semiconductor layer; forming the second conductive semiconductor layer on the active layer; forming the phosphor receiving member having the plurality of the cavities on the second conductive semiconductor layer; and the phosphor layer by fixing the phosphor particles on the plurality of the cavities of the phosphor receiving member.

According to the embodiments, there is provided the light-emitting device and the method for manufacturing the same that can easily and precisely control the distribution position and distribution degree of the phosphor on the light-emitting device and prevents a waste of the phosphor materials upon processing.

In addition, according to one aspect of the embodiment, there is provided the light-emitting device and the method for manufacturing the same that has the improved light efficiency on the surface of the light-emitting device chip, and can be removed with air layer obstructing the total reflection.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, the light-emitting device and the method for manufacturing the same according to the embodiments will be described in detail with reference to the appended drawings. For the description of the embodiments, in the case of describing as forming each layer (film), portions, patterns or structures “on” or “under” substrates, each layer (film), portions, pads or patterns, “on” or “under” includes all of “directly” or “indirectly” formed things. In addition, a standard about “on” or “under” each layer will be described based on the drawings. In the drawings, a thickness or size of each layer is shown roughly, exaggeratedly, or briefly for convenience sake of the description or for a definite description. In addition, a size of each element does not reflect entirely real size.

FIG. 1is a perspective diagram illustrating a light-emitting device according to an embodiment of the present invention.

As shown inFIG. 1, a light-emitting device100includes a substrate110, a first conductive semiconductor layer120formed on the substrate110; a active layer130formed on the first conductive semiconductor layer120; a second conductive semiconductor layer140formed on the active layer130; and a phosphor layer150formed on the second conductive semiconductor layer140.

The substrate110may comprise at least one of Al2O3, SiC, Si, GaAs, GaN, ZnO, GaP, InP and Ge, and may have a conductive property. In addition, the substrate110can be also applicable to a vertical chip by removing the substrate after Epi growth. In this case, Physical Grinding, Laser Lift Off (LLO), Chemical Wet Etching, and the like can remove the substrate.

The first conductive semiconductor layer120can be an n-type semiconductor layer having at least one layer doped with a first conductive dopant. The first conductive semiconductor layer120can be formed with at least one of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, and InP. When setting the first conductive semiconductor layer120as an electron injection layer, the first conductive dopant may include n-type dopant such as Si, Ge, Sn, Se, Te. The first conductive dopant may function as the electrode contact layer hereafter.

The active layer130is formed as a single quantum well or multi quantum well (MQW) structure on the first conductive semiconductor layer120. The active layer130can emit a chromatic light (for example: blue, green, red, etc) or an ultraviolet light. The active layer130may be formed by InGaN/GaN, AlGaN/GaN, or InAlGaN/GaN, GaAs/AlGaAs (InGaAs), GaP/AlGaP(InGaP), and the like, and can adjust a wavelengths of light emitted according to a band gap energy of a material that forms a well layer or barrier layer. For example, in the case of a blue light-emitting of 460˜470 nm wavelengths, InGaN well layer/GaN barrier layer can be formed as one period.

The second conductive semiconductor layer140can be implemented as p-type semiconductor doped with the second conductive dopant on the active layer130. The second conductive semiconductor layer140may include any one of compound semiconductors, such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, InP, and the like. P-type dopant such as Mg, Zn, Ca, Sr, Ba, etc. can be added to the second conductive semiconductor layer140.

The phosphor layer150can be formed on the second conductive semiconductor layer140. The phosphor layer150can be formed as an uniformly distributed and fixed phosphor that is a particle. The phosphor layer150includes the phosphor receiving member152that has the plurality of cavities155for fixing of the phosphor and the phosphor particles200fixed in the cavities155.

The phosphor particles200have a corresponding shape to the cavities155shape, and may be injected and fixed in the cavities155of the phosphor receiving member152, thereby forming the phosphor layer150. Therefore, the phosphor can be distributed uniformly, and the light-emitting efficiency can be improved by forming a photonic crystal type when forming the cavities155. In addition, by forming the phosphor layer150to be overlapped in the light-emitting portion of the second conductive semiconductor layer140, there is an effect that an air layer having a different refractive index is removed, and the total reflection can be reduced, so that a color distribution can be narrowed. According to the embodiments of the present invention, the light emitted from the active layer130emits to outside through the second conductive semiconductor layer140and the phosphor layer150. Therefore, the light emitted from the active layer130can be converted to a light having a different wavelengths in the phosphor layer, and emit as the chromatic light or white light type having fixed colors, so that a light extraction efficiency can be improved by the photonic crystal shape of the phosphor layer150.

Meanwhile, the description as mentioned above illustrates when positioning the active layer130having the quantum well between the first conductive semiconductor layer120formed as a n-type GaN that is basically made of GaN based material and the electron injection layer and the second conductive semiconductor layer140formed as a p-type GaN that is a hole injection layer. However the order of layers can be changed by forming the first conductive semiconductor layer as the p-type semiconductor and the second conductive semiconductor layer as the n-type semiconductor.

FIG. 2toFIG. 4are diagrams to illustrate manufacturing the light-emitting device according to the embodiments of the present invention, and illustrate manufacturing the phosphor layer150.

As shown inFIG. 2, a mixed liquid of the phosphor320is injected in a mold which resembles the shape of the phosphor particles200in order to form the phosphor particles200.

A shape of the phosphor particles200in the mold300is a concave portion310, so that the mold receives the mixed liquid of the phosphor320. The concave portion310can be formed as a spherical like shape, a polygonal shape, a conical shape, a truncated pyramidal shape, a rectangular shape, and a cylindrical shape, etc. according to the shape of the phosphor particles200to be formed. In addition, the concave portion310can be formed as a various size from several um to at least 1 mm size according to the size of the phosphor particles200. In this case, the mold300can be possible to be configured a type to complete the phosphor particles200shapes by matching each other according to the shape of the phosphor particles200.

The mixed liquid of the phosphor320can be made by mixing the phosphor and resin. Various species of R. G. B. phosphor, such as silicate series, sulfide series, garnet series, nitride series, yttrium, aluminum, etc. can be selectively applied to the mixed phosphor. The resin forming the mixed liquid of the phosphor is a material available to be mixed or harden can employ various materials, such as silicone or a transparent epoxy resin, etc. The fixed solvent can be added to the mixed liquid of the phosphor and resin in order to control a viscosity.

FIG. 3illustrates separating of the phosphor particles200.

The phosphor particles200according to the concave shape are formed by charging the mixed liquid of the phosphor320to the concave portion310of the mold300, and then hardening,

The phosphor particles200having a regular shape can be achieved by separating the hardened phosphor particles200from the mold300. Therefore, a leaking or hardening of the phosphor before use can be prevented by forming the phosphor particles200by preparing the mixed liquid of the phosphor320merely when it is needed and charging it to the concave portion310.

FIG. 4illustrates a method for manufacturing the phosphor layer150of the light-emitting device.

The phosphor receiving member152having the plurality of the cavities for fixing the phosphor particles200is formed on the second conductive semiconductor layer140. The phosphor layer150is formed on the second conductive semiconductor layer140by applying the phosphor particles200in the phosphor receiving member152having the cavities155and hardening. The phosphor particles200received in the cavities155can be fixed by using the resin, or can be fixed through the hardening process. In this case, the phosphor particles200remained after being received in the cavities155among the phosphor particles200applied in the phosphor receiving member152can be reused, so that the waste of the phosphor materials can be prevented.

The cavities155formed in the phosphor receiving member152can be employed with Reactive Ion Etching (RIE) by using a photo resistor, Nano Imprinting, Tape Adhesive way, etc. In this case, the shape of the cavities155can be formed to match with the shape of the phosphor particles200, and the light-emitting properties of the light-emitting device can be adjusted by controlling the arrangement way, arrangement distance, and the like. The phosphor particles200are received in the cavities155by applying the phosphor particles200in the phosphor receiving member152having the cavities155. The light can be distributed uniformly by inserting one of the e phosphor particles200in each of cavities155. However, it may also be possible that one cavity receives more that one phosphor particle200according to the cavities155and the sizes or shapes of the phosphor particles200.

FIG. 5is an exemplary diagram illustrating the phosphor particles of the light-emitting device according to the embodiments of the present invention.

A chromaticity, light-emitting properties, light efficiency of the light-emitting device100can be adjusted by varying the size and shape of the phosphor particles200. Therefore, the phosphor particles200having various sizes and shapes can be applied according to the properties of the applied phosphor, a design requirement of the light-emitting device100, and the like.

FIG. 5Aillustrates the phosphor particles, in which its cross-section is an equilateral triangle,FIG. 5Billustrates the phosphor having a regular hexahedron shape.FIG. 5Cillustrates the phosphor particles, in which its cross-section is an octahedron, andFIG. 5Dillustrates the phosphor particles, in which its cross-section is a rhombohedral shape.FIG. 5Eillustrates the phosphor particles, in which its cross-section is a trapezoidal, andFIG. 5Fillustrates the phosphor particles, in which its cross-section is a cylindrical.FIG. 5Gillustrates the phosphor particles, in which its cross-section is a right-angled triangle, andFIG. 5Hillustrates the phosphor particles, in which its cross-section is a parallelogram.

As shown inFIGS. 5A to 5H, the phosphor particles can be formed as various polygonal shapes, such as a polyhedron, horn, column, etc, and will not be limited thereto, can employ the phosphor particles having various shapes, such as regular truncated pyramid shape, spherical shape, and the like.

FIG. 6is a perspective view illustrating the light-emitting device according to another embodiment of the present invention.

The light-emitting device includes a metal layer510, the first conductive semiconductor layer520formed on the metal layer510, the active layer530formed on the first conductive semiconductor layer520, the second conductive semiconductor layer540formed on the active layer530, and the phosphor layer550formed on the second conductive semiconductor layer540.

The metal layer510can be made of at least one of Al, Ag, Pd, Rh, Pt, and the like, and alloys thereof.

The first conductive semiconductor layer520can be implemented as the p-type semiconductor layer doped with the first conductive dopant on the metal layer510. The second conductive semiconductor layer540can be made of any one of compound semiconductors, such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, InP, and the like.

The second conductive dopant may include p-type dopant such as Mg, Zn, Ca, Sr, Ba, and the like.

The active layer530is formed as the single quantum well or multi quantum well (MQW) structure on the first conductive semiconductor layer520. The active layer530can emit the chromatic light (for example: blue, green, red, etc) or the ultraviolet light. Forming the active layer530can be available to use InGaN/GaN, AlGaN/GaN, or InAlGaN/GaN, GaAs/AlGaAs (InGaAs), GaP/AlGaP(InGaP), and the like, and can adjust the wavelengths of light emitted according to the band gap energy of the material that forms the well layer or barrier layer. For example, in the case of the blue light-emitting of 460˜470 nm wavelengths, InGaN well layer/GaN barrier layer can be formed as one period.

The second conductive semiconductor layer540can be implemented as the n-type semiconductor doped with the second conductive dopant on the active layer530. The first conductive semiconductor layer520can be made of any one of compound semiconductors, such as GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, InP, and the like.

When setting the first conductive semiconductor layer120as an electron injection layer, the first conductive dopant may include n-type dopant such as Si, Ge, Sn, Se, Te.

The phosphor layer550can be formed on the second conductive semiconductor layer540.

The phosphor layer550can be formed as an uniformly distributed and fixed phosphor that is a particle. The plurality of the cavities555is formed on the second conductive semiconductor layer540for fixing the phosphor. The phosphor particles250have a shape corresponding to the shape of the cavities555, and form the phosphor layer550by inserting and fixing in the cavities555.

FIG. 7is a phase diagram for manufacturing the light-emitting device500according to other embodiment of the present invention, and illustrates a formation phase of the phosphor layer550ofFIG. 6.

As shown inFIG. 7, the phosphor receiving member552having the plurality of the cavities555in which its cross-section is an octagon is formed on the second conductive semiconductor layer540. The cavities555having the octagon cross-section can be formed at a uniform distance from one another by employing Reactive Ion Etching, Wet Etching, Nano Imprinting, and the like.

The phosphor particles250are polyhedron particles having the octagon cross-section, and can be provided as the hardened type of the resin and the phosphor.

Each cavity555receives the phosphor particles250by applying the phosphor particles250to the phosphor receiving member552having the cavities555. In this case, the remained phosphor particles that are not received in the cavities can be collected and can be re-used.

When inserting the phosphor particles250to the cavities555, the phosphor layer550can be formed on the second conductive semiconductor layer540by fixing using the resin or hardening itself.

According to the embodiments as mentioned above, size and arrangement distance of the phosphor particles can be controlled, so that the chromaticity can be easily and precisely adjusted, and the chromatic distribution can be narrowed. In addition, the waste of the phosphor material upon processing can be prevented by employing as the shape of the phosphor particles250of the phosphor. And the light-emitting efficiency can be improved by forming a photonic crystal type when forming the cavities155.

Features, structures, effect, and the like as mentioned in the embodiment as mentioned above are included in at least one embodiment of the present invention, and will not be limited thereto. In addition, Features, structures, effect, and the like as illustrated in each embodiment of the present invention can be combined and modified by those skilled in the prior arts field. Therefore, it should be understood that the contents related to the combinations and modifications are included in the scope of the present invention.

In addition, the embodiments were described as mentioned above, but they are only examples, and cannot be limited thereto. If the person have skills about the prior art field, they can modify and be applicable within the essential scope of the present invention. For example, each element that is described in the embodiments can be modified and be performed. And it should be understood that the difference related to the modifications and the applications is included in the scope of the present invention as defined in the appended claims.