CN210040240U

CN210040240U - Light emitting diode

Info

Publication number: CN210040240U
Application number: CN201920595157.1U
Authority: CN
Inventors: 吴永胜; 汪雪琴; 林昌江
Original assignee: Fujian Trillion Photoelectric Co Ltd
Current assignee: Fujian Trillion Photoelectric Co Ltd
Priority date: 2019-04-28
Filing date: 2019-04-28
Publication date: 2020-02-07
Anticipated expiration: 2029-04-28

Abstract

The utility model relates to a light emitting diode. The method comprises the following steps: a substrate; an N-type semiconductor layer formed on the substrate; an active layer formed on a partial region of the N-type semiconductor layer; a P-type semiconductor layer formed on the active layer; a transparent conductive layer formed on the P-type semiconductor layer; the P-type electrode is electrically connected with the P-type semiconductor layer; an N-type electrode electrically connected with the N-type semiconductor layer; the N-type electrode and the P-type electrode respectively comprise an ohmic contact layer, a reflecting layer formed on the ohmic contact layer, a conductive metal layer formed on the reflecting layer and a covering layer formed on the conductive metal layer; the ohmic contact layer is a Wyle semi-metal layer. The utility model discloses a light emitting diode's ohmic contact layer structure has low impedance value when the circular telegram, reduces the current loss who appears between electrode and semiconductor layer, can improve light emitting diode's light release efficiency.

Description

Light emitting diode

Technical Field

The present invention relates to a light emitting diode, and more particularly, to a light emitting diode including an ohmic contact layer for ohmic contact between an electrode and a semiconductor layer.

Background

When a forward voltage is applied to the light emitting element, holes in the P-type semiconductor layer are recombined with electrons in the N-type semiconductor layer, and light having a wavelength corresponding to the band gap energy is emitted from the semiconductor light emitting element. Gallium nitride semiconductor (Al)_xIn_yGa_1-x-yN; x is 0. ltoreq. x.ltoreq.1, y is 0. ltoreq. y.ltoreq.1, and x + y is 0. ltoreq. x + y.ltoreq.1) to make the compounding ratio of aluminum, indium, and gallium different, thereby making it possible to emit light of various wavelengths, and has attracted attention as a material for a light-emitting element.

The electrode used in the semiconductor light emitting element should satisfy requirements such as low non-contact resistance, uniform current diffusion, efficient heat dissipation, transparency required for increasing external photon discharge efficiency, or high reflectance. Therefore, a multilayer-structured electrode intended to satisfy such a requirement is being developed and studied.

In order to satisfy the requirement of low non-contact resistance, it is important to realize Ohmic contact (Ohmic contact) for reducing a Schottky barrier (Schottky barrier) at an interface between a gallium nitride semiconductor and an electrode. The N-type gallium nitride semiconductor layer is easy to increase the doping concentration, has a small work function, and is relatively easy to form ohmic contact. In contrast, the P-type gallium nitride semiconductor layer is considered to be almost impossible to form ohmic contact due to a low hole concentration and a high work function of 6.5 eV or more.

Therefore, it is required to develop an electrode structure that enables ohmic contact between a gallium nitride-based semiconductor and an electrode and has low non-contact resistance.

Disclosure of Invention

An object of the utility model is to provide a light emitting diode has low impedance value when the circular telegram, reduces the current loss who appears between electrode and semiconductor layer, can improve light emitting diode's light release efficiency.

In order to achieve the above purpose, the technical scheme of the utility model is that: a light emitting diode comprising:

a substrate;

an N-type semiconductor layer formed on the substrate;

an active layer formed on a partial region of the N-type semiconductor layer;

a P-type semiconductor layer formed on the active layer;

a transparent conductive layer formed on the P-type semiconductor layer;

the P-type electrode is electrically connected with the P-type semiconductor layer;

an N-type electrode electrically connected with the N-type semiconductor layer;

the N-type electrode and the P-type electrode respectively comprise an ohmic contact layer, a reflecting layer formed on the ohmic contact layer, a conductive metal layer formed on the reflecting layer and a covering layer formed on the conductive metal layer; the ohmic contact layer is a Wyle semi-metal layer.

In an embodiment of the present invention, the ohmic contact layer is Bi_1-xSb_xWherein 0 is<x<1。

In an embodiment of the present invention, x is 0.04.

In an embodiment of the invention, the ohmic contact layer further includes a chromium layer formed on the Wyle semi-metal layer.

In an embodiment of the invention, the material of the reflective layer includes aluminum (Al) or silver (Ag), the material of the conductive metal layer includes nickel (Ni), titanium (Ti) or chromium (Cr), and the material of the capping layer includes platinum (Pt) or gold (Au).

Compared with the prior art, the utility model discloses following beneficial effect has: the utility model discloses a light emitting diode's ohmic contact layer structure has low impedance value when the circular telegram, reduces the current loss who appears between electrode and semiconductor layer, can improve light emitting diode's light release efficiency.

Drawings

Fig. 1 is a top view illustrating a light emitting diode according to an embodiment of the present invention.

Fig. 2 is a sectional view (2a) showing a section taken along line a-a 'and a sectional view (2B) showing a section taken along line B-B' of the light emitting diode shown in fig. 1.

Fig. 3 is a sectional view illustrating an electrode structure of a light emitting diode according to an embodiment of the present invention.

In the figure:

10 base plate

20 light-emitting structure

21: N type semiconductor layer

23 active layer

25P-type semiconductor layer

30 electrode structure

31P-type electrode

33P-type finger electrode

35N type electrode

37N-type finger electrode

40 ohmic contact layer

51 transparent electrode layer

Current blocking layer 53

60 passivation layer

71 reflective layer

73 conductive metal layer

And 75, covering layer.

Detailed Description

The invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. However, the present invention is not limited to the specific forms disclosed, but on the contrary, the present invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.

When an element such as a layer, region or substrate is referred to as being "on" another constituent element, it can be directly on the other element or intervening elements may also be present therebetween.

The terms first, second, etc. may be used for describing various elements, components, regions, layers and/or regions, but it should be understood that such elements, components, regions, layers and/or regions are not limited by such terms.

Preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. The same components in the following drawings are denoted by the same reference numerals, and redundant description thereof will be omitted.

Examples

Referring to fig. 1, a light emitting diode according to an embodiment of the present invention includes: a light-emitting structure (20) including an N-type semiconductor layer, an active layer, and a P-type semiconductor layer; a P-type electrode (31) electrically connected to the P-type semiconductor layer; and an N-type electrode (35) electrically connected to the N-type semiconductor layer.

Optionally, the light emitting diode may further include P-type finger electrodes (33) and N-type finger electrodes (37) for uniformly diffusing current on the P-type semiconductor layer. The P-type finger electrode (33) is formed on the P-type semiconductor layer and extends from the P-type electrode (31) toward the N-type electrode (35).

The N-type finger electrode (37) is formed on the N-type semiconductor layer so as to extend from the N-type electrode (35) and surround the P-type finger electrode (33). Therefore, current can be efficiently transmitted to the entire region of the light-emitting structure (20).

Referring to fig. 2, a light emitting diode according to an embodiment of the present invention includes: a substrate (10); a light-emitting structure (20) formed on the substrate (10), and including an N-type semiconductor layer (21), an active layer (23), and a P-type semiconductor layer (25); an electrode structure (30) including a P-type electrode (31) formed on the light emitting structure (20) and electrically connected to the P-type semiconductor layer (25), a P-type finger electrode (33) extended from the selectively formed P-type electrode (31), an N-type electrode (35) electrically connected to the N-type semiconductor layer (21), and an N-type finger electrode (37) extended from the selectively formed N-type electrode (35); and a passivation layer (60).

If referring to fig. 2, the light emitting diode of an embodiment of the present invention includes: a substrate (10); a light-emitting structure (20) formed on the substrate (10), and including an N-type semiconductor layer (21), an active layer (23), and a P-type semiconductor layer (25); an electrode structure (30) formed on the light-emitting structure (20), and including a P-type electrode (31) electrically connected to the P-type semiconductor layer (25), a P-type finger electrode (33) extending from the P-type electrode (31), an N-type electrode (35) electrically connected to the N-type semiconductor layer (21), and an N-type finger electrode (37) extending from the N-type electrode (35); and a passivation layer (60).

The substrate (10) can be used without limitation as long as it is a known substance that can be used as a gallium nitride-based light emitting diode substrate. Generally, SiC, Si, GaN, ZnO, GaAs, GaP, LiAl capable of growing gallium nitride semiconductor material may be used₂O₃Any one of BN, AlN and the like, but not limited thereto. The substrate (10) may have a concave-convex pattern in order to grow a high-quality gallium nitride light-emitting structure (20), reflect light formed from the active layer (23), and increase optical power.

A gallium nitride-based light-emitting structure (20) is formed on the substrate (10). First, an n-type semiconductor layer (21) is formed on a substrate (10). An active layer (23) is formed on the n-type semiconductor layer (21). A p-type semiconductor layer (25) is formed on the active layer (23). A part of the regions of the p-type semiconductor layer (25) and the active layer (23) is etched to expose the n-type semiconductor layer (21).

The light emitting structure (20) may be Al_xIn_yGa_1-x-yN (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1), the N-type semiconductor layer (21) may include an N-type dopant such as silicon (Si), germanium (Ge), or tin (Sn), and the p-type semiconductor layer (25) may include a p-type dopant such as magnesium (Mg), zinc (Zn), or cadmium (Cd). The active layer (23) may have a single quantum well structure orA multiple quantum well structure. The active layer (23) of the multiple quantum well structure may have a structure in which a semiconductor layer having a large band gap and a small semiconductor layer are alternately stacked.

The n-type semiconductor layer (21), the active layer (23), and the p-type semiconductor layer (25) may be formed by means of Chemical Vapor Deposition (CVD), or may be formed by means of a known deposition method such as Physical vapor deposition (Physical vapor deposition), sputtering (sputtering), hydrogen vapor deposition (HVPE), or Atomic layer deposition (Atomic layer deposition).

A transparent conductive layer (51) can be selectively formed on the p-type semiconductor layer (25). The transparent conductive layer (51) can be formed as a very thin Ni/Au film or a conductive metal oxide film. The transparent conductive layer (51) can diffuse current to the p-type semiconductor layer (25) having a low hole density.

When the transparent conductive layer (51) is formed, a current blocking layer (53) can be formed in a partial region on the p-type semiconductor layer (25). The current blocking layer (53) is formed in a region below the p-type electrode (31) and prevents current from flowing from below the p-type electrode (31) into the active region. Therefore, current meanders from the p-type electrode (31), and thus light emission efficiency can be improved.

A P-type electrode (31) is formed on the P-type semiconductor layer (25) or the transparent conductive layer (51). An N-type electrode (35) is formed on the N-type semiconductor layer (21) exposed from the active layer (23) and the P-type semiconductor layer (25).

P-type finger electrodes (33) are formed to extend from the P-type electrodes (31) toward the N-type electrodes (35). An N-type finger electrode (37) is formed so as to extend from the N-type electrode (31) and surround the P-type finger electrode (33). The electrode structure (30) including the P-type electrode (31), the N-type electrode (35), the P-type finger electrode (33), and the N-type finger electrode (37) may have various shapes for effectively diffusing current to the light emitting structure (20).

The electrode structure (30) may be formed by means of a well-known deposition method such as Physical vapor deposition (Physical vapor deposition), sputtering (sputtering), hydrogen vapor deposition (HVPE), or Atomic layer deposition (Atomic layer deposition).

An ohmic contact layer (40) is formed on the lower portion of the electrode structure (30). The ohmic contact layer (40) is used as a Wyle semi-metal (Wyle semi-metal) layer and can be Bi_1-xSb_xWherein, 0<x<1, but not limited thereto. The x may be 0.04, but is not limited thereto. The ohmic contact layer (40) may further include a chromium (Cr) layer on the Wyle semi-metal layer.

A passivation layer (60) is formed to surround the light-emitting structure (20) and the electrode structure (30). The passivation layer (60) is formed to prevent a reduction in light emitting efficiency due to physical, chemical, and electrical damage. The passivation layer (60) may contain phosphors necessary for forming a white light emitting diode. The phosphor may be yag (yttrium aluminum garnet) as a yellow phosphor.

Referring to fig. 3, the electrode structure (30) may have a multilayer structure including a reflective layer (71), a conductive metal layer (73), and a cover layer (77) formed on the ohmic contact layer (40).

The reflective layer (71) contains aluminum (Al) or silver (Ag), and reflects light emitted in the active region, thereby preventing the light from being absorbed by the conductive metal layer (73).

The conductive metal layer (73) may include nickel (Ni), titanium (Ti), or chromium (Cr).

A cover layer (75) formed on the conductive metal layer (73) prevents the conductive metal layer (73) from being chemically damaged or oxidized. The capping layer (75) may include platinum (Pt) or gold (Au).

Above is the utility model discloses a preferred embodiment, all rely on the utility model discloses the change that technical scheme made, produced functional action does not surpass the utility model discloses during technical scheme's scope, all belong to the utility model discloses a protection scope.

Claims

1. A light emitting diode, comprising:

a substrate;

an N-type semiconductor layer formed on the substrate;

an active layer formed on a partial region of the N-type semiconductor layer;

a P-type semiconductor layer formed on the active layer;

a transparent conductive layer formed on the P-type semiconductor layer;

an N-type electrode electrically connected with the N-type semiconductor layer;

the N-type electrode and the P-type electrode respectively comprise an ohmic contact layer, a reflecting layer formed on the ohmic contact layer, a conductive metal layer formed on the reflecting layer and a covering layer formed on the conductive metal layer; the ohmic contact layer is a Wyle semi-metal layer; the ohmic contact layer is Bi_1-xSb_xWherein 0 is<x<1。

2. The led of claim 1, wherein x is 0.04.

3. The led of claim 1, wherein said ohmic contact layer further comprises a chromium layer formed on said Wyle semi-metal layer.

4. The led of claim 1, wherein the reflective layer comprises aluminum (Al) or silver (Ag), the conductive metal layer comprises nickel (Ni), titanium (Ti), or chromium (Cr), and the capping layer comprises platinum (Pt) or gold (Au).