JP2015026656A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device with high reflectance.SOLUTION: A light-emitting device comprises: a light emission stack layer comprising an active layer; and a non-oxide insulation layer located lower the light emission stack layer. The non-oxide insulation layer of them has a refraction index lower than 1.4.

Description

  The present invention relates to a light emitting element, and more particularly to a light emitting element having a high reflectance.

  Photoelectric elements such as light-emitting diodes (LEDs) are currently widely used in optical display devices, traffic signs, data storage devices, communication devices, lighting devices, and medical equipment. The above-described LED can be connected in combination with another element to form a light-emitting device. FIG. 1 is a structural diagram of a conventional light emitting device. As shown in FIG. 1, the light emitting device 1 includes a submount 12 having a circuit 14; a solder 16 located on the submount 12 described above, and the LED 11 is fixed to the submount 12 by the solder 16. And solder 16 for electrically connecting the circuit 14 of the submount 12; and an electrical connection structure 18 for electrically connecting the electrode 15 of the LED 11 and the circuit 14 of the submount 12, of which the above-mentioned The submount 12 may be, for example, a lead frame or a large size mounting substrate.

  An object of the present invention is to provide a light emitting device having high reflectivity.

  A light emitting device according to an embodiment of the present invention includes a light emitting stack layer including an active layer and a non-oxide insulating layer positioned under the light emitting stack layer, wherein the refractive index of the non-oxide insulating layer is: Less than 1.4.

It is a structural diagram of a conventional light emitting device. 1 is a top view of a light emitting device according to an embodiment of the present invention. FIG. 2B is a cross-sectional view taken along line AA ′ of FIG. 2A. FIG. 5 is a graph showing the relationship between the power of the surface area of the first contact upper surface relative to the sum of the surface areas of the first contact upper surface and the second contact upper surface. 1 is an exploded view of a lamp according to an embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  2A is a top view of a light emitting device according to an embodiment of the present invention, and FIG. 2B is a cross-sectional view taken along line AA ′ of FIG. 2A. As shown in FIG. 2B, the light-emitting element 2 is located on the substrate 20; the conductive adhesive layer 21 located on the substrate 20; the reflective structure 22 located on the conductive adhesive layer 20; Transparent conductive structure 23; window layer 29 positioned on transparent conductive structure 23; non-oxide insulating layer 24 positioned between transparent conductive structure 23 and window layer 29; light emitting stack layer positioned on window layer 29 25; an electrical contact layer 26 located on the light emitting stack layer 25; a first electrode 27 located on the light emitting stack layer 25 and the electrical contact layer 26; and a second electrode 28 located below the substrate 20 . The light emitting stack layer 25 includes a first semiconductor layer 251 positioned between the window layer 29 and the first electrode 27; an active layer 252 positioned between the first semiconductor layer 251 and the first electrode 27; and an active layer A second semiconductor layer 253 is provided between 252 and the first electrode 27.

  The first electrode 27 and / or the second electrode 28 are for receiving an external voltage, and may be made of a transparent conductive material or a metal material. The transparent conductive material may include ITO, InO, SnO, CTO, ATO, AZO, ZTO, GZO, IWO, ZnO, AlGaAs, GaN, GaP, GaAs, GaAsP, IZO, or DLC (diamond-like carbon). However, it is not limited to these. The metal material may include, but is not limited to, Al, Cr, Cu, Sn, Au, Ni, Ti, Pt, Pb, Zn, Cd, Sb, Co, or an alloy of the above materials. The first electrode 27 has a current injection part 271 and an extension part 272. As shown in FIG. 2A, the current injection part 271 is located substantially above the center of the second semiconductor layer 253, and the extension part 272 extends from the current injection part 271 to the boundary of the light emitting element 2. And a second wire 2722 extending from the first wire 2721, thereby improving current spreading. As shown in FIG. 2B, the extending portion 272 includes a protrusion 273 located on the electric contact layer 26, and the protrusion 273 covers at least one surface of the electric contact layer 26, whereby the electric contact The area of the ohmic contact formed with the layer 26 is increased, and the resistance of the light emitting element 2 is decreased, and the protrusion 273 is higher than the current injection portion 271.

  The electrical contact layer 26 is located between the second wire 2722 and the light emitting stack layer 25 and is used to form an ohmic contact between the second wire 2722 and the light emitting stack layer 25. The resistance value between the electrical contact layer 26 and the second wire 2722, and the resistance value between the electrical contact layer 26 and the light emitting stack layer 25 are respectively between the first electrode 27 and the light emitting stack layer 25. Less than the resistance value. The material of the electrical contact layer 26 may be a semiconductor material containing one or more elements selected from the group consisting of Ga, Al, In, P, N, Zn, Cd, and Se. The electrical characteristics may be the same as those of the second semiconductor layer 253.

  The material of the light emitting stack layer 25 may be a semiconductor material containing one or more elements selected from the group consisting of Ga, Al, In, P, N, Zn, Cd, and Se. The first semiconductor layer 251 and the second semiconductor layer 253 have different electrical characteristics, thereby generating electrons or holes. The light emitting upper surface 254 of the second semiconductor layer 253 may be a rough surface, thereby suppressing (decreasing) total reflection and improving the light emission efficiency of the photoelectric element 2. The active layer 252 can emit light of one or more colors, such light may be visible light or invisible light, and the structure of the active layer 252 is a single heterostructure, It may be a double heterostructure, a double heterostructure on both sides, a multilayer quantum well, or a quantum dot. The electrical characteristics of the window layer 29 may be the same as the electrical characteristics of the first semiconductor layer 251, and may be used as a light extraction layer, thereby improving the light emission efficiency of the light emitting element 2. The window layer 29 is transparent to the light emitted from the active layer 252, and the material thereof may be a transparent conductive material, ITO, InO, SnO, CTO, ATO, AZO, ZTO, GZO, IWO, ZnO, MgO, AlGaAs, GaN, GaP, or IZO may be included, but is not limited thereto.

  The transparent conductive structure 23 is transparent to the light emitted by the light emitting stack layer 25, and is used to increase ohmic contact, current conduction and diffusion between the window layer 251 and the reflective structure 22, and An omni-directional reflector (ODR) can be formed together with the reflecting structure 22. The material may be a transparent conductive material, ITO, InO, SnO, CTO, ATO, AZO, ZTO, GZO, IWO, ZnO, GaP, ICO, IWO, ITiO, IZO, IGO, GAZO, or the above-mentioned A combination of these materials may also be included, but is not limited to these. The transparent conductive structure 23 includes a first conductive oxide layer 230 positioned under the non-oxide insulating layer 24, and a second conductive oxide layer 232 positioned between the light emitting stack layer 25 and the first conductive oxide layer 230. Have. Among them, the materials of the first conductive oxide layer 230 and the second conductive oxide layer 232 are different. In another embodiment, the material of the first conductive oxide layer 230 and the second conductive oxide layer 232 differ in at least one constituent element, for example, the material of the first conductive oxide layer 230 is IZO, The material of the oxide layer 232 is ITO. The second conductive oxide layer 232 may be in direct contact with the non-oxide insulating layer 24 and / or the window layer 29 and may cover at least one surface of the non-oxidized insulating layer 24.

The transmittance of the non-oxide insulating layer 24 for the light emitted from the light emitting stack layer 25 is greater than 90%, and the refractive index is less than 1.4, preferably between 1.3 and 1.4. The material of the non-oxide insulating layer 24 may be a non-oxide insulating material, for example, benzocyclobutene (BCB), cyclic olefin copolymer (COC), fluorocarbon polymer, SiN _x , CaF ₂ , or, a MgF _2. In other embodiments, the material of the non-oxide insulating layer 24 may include halides or Group IIA and Group VII compounds, such as CaF ₂ or MgF ₂ . The refractive index of the non-oxide insulating layer 24 is smaller than the refractive indexes of the window layer 29 and the transparent conductive structure 23. Since the refractive index of the non-oxide insulating layer 24 is smaller than the refractive index of the window layer 29 and the transparent conductive structure 23, the critical angle of the interface between the window layer 29 and the non-oxide insulating layer 24 is the window layer 29. And the critical angle of the interface between the transparent conductive structure 23 and the transparent conductive structure 23. Therefore, after the light emitted from the light emitting stack layer 25 is emitted to the non-oxide insulating layer 24, the probability of forming total reflection at the interface between the window layer 29 and the non-oxide insulating layer 24 increases. In addition, light that originally enters the transparent conductive structure 23 without forming total reflection at the interface between the window layer 29 and the transparent conductive structure 23 is transmitted to the interface between the transparent conductive structure 23 and the non-oxide insulating layer 24. Since total reflection can also be formed in, the amount of light is increased and the light emission efficiency of the light emitting element 2 is improved. The transparent conductive structure 23 has a first contact upper surface 231 in contact with the window layer 29, and the non-oxide insulating layer 24 has a second contact upper surface 241 in contact with the window layer 29. The surface 231 and the second contact upper surface 241 are substantially in the same horizontal plane, that is, the distance between the first contact upper surface 231 and the light emitting upper surface 254 is approximately the second contact upper surface 241 and the light emitting upper surface 254. Equal to distance from surface 254. FIG. 3 is a relationship diagram between the ratio (percentage) of the surface area of the first contact upper surface 231 to the sum of the surface areas of the first contact upper surface 231 and the second contact upper surface 241 and the power of the light emitting element 2. As shown in FIG. 3, when the surface area of the first contact upper surface 231 is about 10% to 50% with respect to the sum of the surface areas of the first contact upper surface 231 and the second contact upper surface 241, the light-emitting element 2 Its power is above 50mW, which is good compared to the power of a light emitting device whose percentage is above 50. Preferably, the power is above 55 mW when the percentage is about 12.5% to 25%. In other words, when the ratio of the surface area of the non-oxide insulating layer 24 to the window layer 29 and the surface area of the window layer 29 to the non-oxide insulating layer 24 is about 0.5 to 0.9, the power of the light emitting element 2 is good. In other embodiments, the second contact upper surface 241 may be a rough surface, which scatters the light emitted by the light emitting stack layer, thereby improving the light extraction efficiency of the photoelectric element 2. The non-oxide insulating layer 24 may have a patterned distribution, for example, substantially located directly below the electrical contact layer 26 and / or the current injection portion 271, thereby increasing current spreading. In other embodiments, the non-oxide insulating layer 24 may exhibit an irregular distribution or may not be located directly below the electrical contact layer 26 and / or the current injection portion 271. The thickness of the non-oxide insulating layer 24 is smaller than half the thickness of the transparent conductive structure 23. In another embodiment, the thickness of the non-oxide insulating layer 24 is less than 1/5 of the thickness of the transparent conductive structure 23, so that the surface planarization process after the transparent conductive structure 23 is formed is non-oxide. Avoid destroying the structure of the insulating layer 24. At least one surface of the non-oxide insulating layer 24 is covered with the transparent conductive layer 23, thereby strengthening the bonding between the transparent conductive layer 23 and the window layer 29 and improving the mechanical strength of the structure. In other embodiments, the non-oxide insulating layer 24 may be bonded directly to the reflective structure 22, thereby avoiding delamination due to lack of adhesion between the transparent conductive structure 23 and the reflective structure 22. The non-oxide insulating layer 24 further includes a plurality of pores 242 penetrating the non-oxide insulating layer 24, of which the transparent conductive structure 23 fills the plurality of pores 242 and forms an ohmic contact with the window layer 29. To do.

  The reflective structure 22 can reflect the light from the light emitting stack layer 25, and the material thereof may be a metal material, Cu, Al, Sn, Au, Ag, Pb, Ti, Ni, Pt, W Alternatively, an alloy of the above-described materials or the like may be included, but is not limited thereto. The reflective structure 22 includes a reflective layer 226; a reflective adhesive layer 224 located below the reflective layer 226; a barrier layer 222 located below the reflective adhesive layer 224; and an ohmic contact layer located below the barrier layer 222. Includes 220. The reflective layer 226 can reflect the light from the light emitting stack layer 25, the reflective adhesive layer 224 bonds the reflective layer 226 and the barrier layer 222, and the barrier layer 222 is made of the material of the reflective layer 226 as an electrode. It is possible to prevent diffusion to the layer 220, destruction of the structure of the reflective layer 226, and reduction of the reflectance of the reflective layer 226. The ohmic contact layer 220 forms an ohmic contact with the lower conductive adhesive layer 21. The conductive adhesive layer 21 can connect the substrate 20 and the reflective structure 22 and may have a plurality of dependent layers (not shown). The material of the conductive adhesive layer 21 may be a transparent conductive material or a metal material, and the transparent conductive material may be ITO, InO, SnO, CTO, ATO, AZO, ZTO, GZO, ZnO, GaP, ICO, IWO, It may include, but is not limited to, ITiO, IZO, IGO, GAZO, or combinations of the above materials. The metal material may include, but is not limited to, Cu, Al, Sn, Au, Ag, Pb, Ti, Ni, Pt, W, or an alloy of the above materials.

The substrate 20 may be used to support the light emitting stack layer 25 and other layers or structures located thereon, and the material may be a transparent material or a conductive material. The transparent material may include Sapphire, Diamond, Glass, Epoxy, Quartz, Acryl, Al ₂ O ₃ , ZnO, or AlN. However, it is not limited to these. Conductive materials are Cu, Al, Mo, Sn, Zn, Cd, Ni, Co, DLC (Diamond Like Carbon), Graphite, Carbon fiber, Metal Matrix Composite (MMC) Ceramic Matrix Composite (CMC), Si, IP, ZnSe, GaAs, SiC, GaP, GaAsP, InP, LiGaO ₂ , or LiAlO ₂ may be included, but is not limited thereto.

  FIG. 4 is an exploded view of the lamp. The lamp 4 comprises a lamp shade 41; a lens 42 placed in the lamp shade 41; an illumination module 44 located under the lens 42; a heat dissipation groove 46 and a lamp socket 45 for mounting the illumination module 44; And an electrical connector 48, of which the connection unit 47 connects the lamp socket 45 and the electrical connector 48. The lighting module 44 includes a carrier 43 and a plurality of light emitting elements 40 according to any of the above-described embodiments located on the carrier 43.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to this embodiment, and all modifications to the present invention belong to the technical scope of the present invention unless departing from the spirit of the present invention.

1 Light emitting device
11 LED
12 Submount
13, 20 substrate
14 circuits
15 electrodes
16 Solder
18 Electrical connection structure
2, 40 Light emitting device
21 Conductive adhesive layer
22 Reflective structure
220 Ohmic contact layer
222 Barrier layer
224 reflective adhesive layer
226 Reflective layer
23 Transparent conductive structure
230 First conductive oxide layer
231 First contact upper surface
232 Second conductive oxide layer
24 Non-oxide insulating layer
241 Second contact upper surface
242 pores
25 Light emitting stack layer
251 First semiconductor layer
252 Light emitting layer
253 Second semiconductor layer
254 Light output upper surface
26 Electrical contact layer
27 First electrode
271 Current injection part
272 Stretching part
273 Protrusion
2721 1st wire
2722 2nd wire
28 Second electrode
29 Window layer
4 Lamp
41 Lampshade (lamp umbrella)
42 Lens
43 Career
44 Lighting module
45 Lamp socket
46 Radiation groove
47 Connection
48 Electrical connector

Claims (23)

A light emitting device,
A light emitting stack layer including an active layer;
A non-oxide insulating layer connected to the light emitting stack layer,
A light-emitting element having a refractive index of the non-oxide insulating layer of less than 1.4. The light-emitting device according to claim 1,
A window layer positioned between the active layer and the non-oxide insulating layer;
The light emitting element whose refractive index of the said window layer is larger than the refractive index of the said non-oxide insulating layer. The light-emitting device according to claim 1,
The light emitting device further comprising an electrical contact layer located immediately above the non-oxide insulating layer. The light emitting device according to claim 3,
The electrical contact layer is a light emitting device including a semiconductor material. The light emitting device according to claim 3,
The light emitting device further comprising a first electrode positioned on the light emitting stack layer. The light emitting device according to claim 5,
The first electrode includes a protrusion located on the electrical contact layer, and / or the first electrode includes an extending portion that covers the electrical contact layer. The light-emitting device according to claim 1,
The light emitting device, wherein a refractive index of the non-oxide insulating layer is between 1.3 and 1.4. The light-emitting device according to claim 1,
The light emitting device further comprising a reflective layer located under the non-oxide insulating layer. The light emitting device according to claim 8,
The light emitting device, wherein the non-oxide insulating layer and the reflective layer are directly connected to each other. The light emitting device according to claim 8,
A reflective adhesive layer located under the reflective layer;
A barrier layer located under the reflective adhesive layer;
And a ohmic contact layer positioned under the barrier layer. The light-emitting device according to claim 1,
The light emitting device further comprising a transparent conductive structure covering one surface of the non-oxide insulating layer. The light emitting device according to claim 11,
The transparent conductive structure includes a first contact upper surface that contacts the light emitting stack layer;
The non-oxide insulating layer includes a second contact upper surface that contacts the light emitting stack layer;
The light emitting device, wherein the surface area of the first contact upper surface is 10% to 50% with respect to the sum of the surface areas of the first contact upper surface and the second contact upper surface. The light emitting device according to claim 11,
A plurality of pores penetrating the non-oxide insulating layer;
The transparent conductive structure is a light emitting device filled in the plurality of pores. The light emitting device according to claim 11,
The light emitting device, wherein a thickness of the non-oxide insulating layer is smaller than half of a thickness of the transparent conductive structure. The light emitting device according to claim 11,
The light emitting device, wherein a thickness of the non-oxide insulating layer is smaller than 1/5 of a thickness of the transparent conductive structure. The light emitting device according to claim 11,
The transparent conductive structure is
A first conductive oxide layer located under the non-oxide insulating layer;
A light emitting device comprising: the light emitting stack layer; and a second conductive oxide layer positioned between the first conductive oxide layer. The light emitting device according to claim 16,
The light emitting device, wherein the first conductive oxide layer and the second conductive oxide layer are made of different materials. The light-emitting device according to claim 1,
A substrate located under the non-oxide insulating layer;
The light emitting device further comprising: a conductive adhesive layer positioned between the substrate and the non-oxide insulating layer. The light-emitting device according to claim 1,
The non-oxide insulating layer material includes a halide. The light-emitting device according to claim 1,
The non-oxide insulating layer material includes a Group IIA and Group VIIA compound. The light-emitting device according to claim 1,
The light emitting element, wherein the non-oxide insulating layer has a transmittance with respect to light emitted from the active layer of greater than 90%. The light-emitting device according to claim 1,
A window layer positioned between the non-oxide insulating structure and the light emitting stack layer;
A transparent conductive structure located under the window layer and the non-oxide insulating layer;
The light emitting device, wherein a critical angle of an interface between the window layer and the non-oxide insulating layer is smaller than a critical angle of an interface between the window layer and the transparent conductive structure. The light-emitting device according to claim 1,
The light emitting element wherein a ratio of a surface area of the non-oxide insulating layer to the window layer and a surface area of the window layer to the non-oxide insulating layer is 0.5 to 0.9%.

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