WO2016037467A1

WO2016037467A1 - Light-emitting diode

Info

Publication number: WO2016037467A1
Application number: PCT/CN2015/073463
Authority: WO
Inventors: 董木森; 申利莹; 王笃祥; 王良均
Original assignee: 厦门市三安光电科技有限公司
Priority date: 2014-09-10
Filing date: 2015-03-02
Publication date: 2016-03-17
Also published as: CN104201261A

Abstract

A light-emitting diode, comprising in sequence: a substrate (100), a buffer layer (101), an N-type GaN layer (102), an MQW light-emitting layer (103) and a P-type GaN layer (104). The MQW light-emitting layer is formed by alternately stacking a well/base periodically; a well layer (103a) is an In _xGa _1-xN layer; a base layer (103b) is a GaN layer doping N/P simultaneously, which can be uniform doping, non-uniform doping or delta doping; and the number of base layers doping N/P, and an N/P doping period, doping area and doping concentration in the base layer can all be adjusted. By adopting the method of simultaneously performing N/P doping in a GaN base layer of an MQW structure to form a tunnel junction, transmission and diffusion of a hole and an electron in the whole MQW area is improved, so as to broaden a light-emitting area of the MQW and improve the compound probability of the hole and the electron, and improve the light-emitting efficiency of a light-emitting diode.

Description

Light emitting diode

The present application claims priority to Chinese Patent Application No. 201410456524, filed on Sep. 10, 2014, the entire disclosure of which is hereby incorporated by reference.

Technical field

The present invention relates to a semiconductor light emitting device, and more particularly to a light emitting diode.

Background technique

In recent years, as a green light source, light-emitting diodes (LEDs) have been gradually applied in industry and agriculture as well as people's daily life. With its wider application, it is imperative to further improve its efficiency. GaN-based light-emitting diodes The conventional MQW structure (In _x Ga _1-x N/GaN) _n has a hole concentration much smaller than the electron concentration, resulting in a low composite probability and a large illuminating region concentrated in the last few MQWs, thus severely limiting the light-emitting diodes. Luminous efficiency. Therefore, it is necessary to invent a high-efficiency MQW structure to solve the above problems and further improve the luminous efficiency of the light emitting diode.

Summary of the invention

In view of the above problems, the present invention provides a novel and efficient MQW structure to improve the luminous efficiency of a light emitting diode.

A light emitting diode comprising, in order, a substrate, a buffer layer, an N-type GaN layer, an MQW light-emitting layer, and a P-type GaN layer. The MQW light-emitting layer is formed by alternately stacking periodic wells/barriers, and the number of cycles is 2 to 100, preferably 5 to 15. The well layer is an In _x Ga _1-x N layer, 0 < x < 1, preferably 0.1 to 0.4. The barrier layer is a N/P-doped GaN layer, and the number of N/P-doped GaN barrier layers can be adjusted, and 1≤numbers ≤MQW periods.

The N/P doping in the GaN barrier layer may be uniform doping, non-uniform doping or delta doping, and is realized by controlling a switch of the MO source MFC, and the N/P doping sources are preferably SiH ₄ and CP ₂ Mg, respectively. .

The N/P doping period, the doping region, and the doping concentration in the GaN barrier layer can be adjusted. The number of doping cycles is from 1 to 100, preferably from 1 to 3. The doped region is required to be inside the barrier layer, and the two sides of the barrier layer near the well layer are undoped, and the non-doped GaN thickness is ≥5 nm to prevent diffusion of Si/Mg into the well layer in the In barrier layer and the barrier layer in the well layer. . The doping concentration requirement ≤ N/P doping concentration in the N-type GaN layer/P-type GaN layer, ranging from 1 × 10 ¹⁶ to 1 × 10 ²¹ cm ^-3 , preferably 1 × 10 ¹⁷ to 1 × 10 ¹⁸ cm ^{- 3.} It is further preferred that the concentration of N doping in the GaN barrier layer is gradually decreased as it approaches the P-type GaN layer, and the P doping concentration is gradually decreased as it approaches the N-type GaN layer, and may be linearly reduced or nonlinearly reduced.

The high-efficiency light-emitting diode of the present invention has the following beneficial effects as compared with the conventional MQW structure (In _x Ga _1- _x N/GaN) _{n of a} GaN-based light-emitting diode:

(1) Using N/P doped in the MQW structure GaN barrier layer to form a tunneling junction can effectively improve the transmission and diffusion of holes and electrons in the entire MQW region, thereby broadening the light-emitting region of MQW and improving holes and electrons. The composite probability, in the end, can significantly improve the luminous efficiency of the LED;

(2) In the MQW structure, the barrier layer is doped with N/P in various forms, and the design space is large, and the luminous efficiency of the LED can be fully optimized.

DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a In addition, the drawing figures are a summary of the description and are not drawn to scale.

FIG. 1 is a cross-sectional view of a light emitting diode according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of an MQW of a light emitting diode according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of control of a doping form of an MQW structure according to an embodiment of the present invention.

4 is a schematic diagram of control of another doping form of the MQW structure according to an embodiment of the present invention.

The figure indicates:

100: substrate; 101: buffer layer; 102: N-type GaN layer; 103: MQW light-emitting layer; 103a: In _x Ga _1-x N well layer; 103b: GaN barrier layer; 104: P-type GaN layer; N electrode; 106: P electrode; 107: insulating protective layer.

detailed description

The light emitting diode of the present invention will now be described in more detail with reference to the accompanying drawings.

Example

As shown in FIG. 1, the present invention provides a light emitting diode comprising, from bottom to top, in order:

(1) A substrate 100 which is made of sapphire (Al ₂ O ₃ ) or a single crystal oxide whose lattice constant is close to that of a nitride semiconductor, and is preferably a sapphire substrate in this embodiment.

(2) A buffer layer 101 which is grown on the substrate 100 and is a gallium nitride (GaN) and/or aluminum nitride (AlN) layer having a film thickness of 10 nm to 50 nm.

(3) an N-type GaN layer 102 grown on the buffer layer 101 with a film thickness of 100 nm to 1000 nm and a doping concentration of 1 × 10 ¹⁸ to 1 × 10 ²⁰ cm ^-3 , preferably 1 ×10 ¹⁹ cm ^-3 , the doping source is preferably SiH ₄ .

(4) An MQW light-emitting layer 103, the MQW light-emitting layer being grown on the N-type GaN layer 102. The MQW light-emitting layer 103 is alternately stacked by periodic wells/barriers. As shown in FIG. 2, the number of periods is 2 to 100, preferably 5 to 15.

The well layer 103a is an In _x Ga _1-x N layer, the In source is TMIn, the Ga source is TMGa or TEGa, and the N source is NH ₃ , and the film thickness is 1 nm to 10 nm, 0<x<1, preferably 0.1 to 0.4. .

The barrier layer 103b is a N/P-doped GaN layer, the Ga source is TMGa or TEGa, the N source is NH ₃ , the film thickness is 10 nm to 30 nm, and the number of N/P-doped GaN barrier layers can be adjusted. 1 ≤ number ≤ number of MQW cycles.

The N/P doping in the GaN barrier layer 103b may be uniform doping (as shown in FIG. 3), non-uniform doping (as shown in FIG. 3), or delta doping (as shown in FIG. 4). The switch of the MO source MFC is realized, and the N/P doping sources are preferably SiH ₄ and CP ₂ Mg, respectively.

The N/P doping period, the doping region, and the doping concentration in the GaN barrier layer 103b can be adjusted. The number of doping cycles is from 1 to 100, preferably from 1 to 3. The doped region is required to be inside the barrier layer, and the both sides of the barrier layer near the well layer are undoped, and the non-doped GaN thickness is ≥5 nm to prevent Si/Mg from being trapped in the In barrier layer 103b and the barrier layer 103b in the well layer 103a. Diffusion of layer 103a. The doping concentration requirement ≤ N/P doping concentration in the N-type GaN layer 102/P-type GaN layer 104, in the range of 1 × 10 ¹⁶ to 1 × 10 ²¹ cm ^-3 , preferably 1 × 10 ¹⁷ to 1 × 10 ¹⁸ cm ^-3, more preferably the N-GaN barrier layer 103b is decreased doping concentration near the P-type GaN layer 104, the concentration of P-doped N-type GaN layer close to 102 gradually decreases, reducing the tendency may be reduced or non-linear.

(5) a P-type GaN layer 104 grown on the MQW light-emitting layer 103 with a film thickness of 100 nm to 300 nm and a doping concentration of 1 × 10 ¹⁹ to 1 × 10 ²¹ cm ^-3 , preferably 1 × 10 ²⁰ cm ^-3 , and the doping source is preferably CP ₂ Mg.

(6) an N electrode 105 which is formed in a portion of the N-type GaN layer 102 exposed by the etching process Above.

(7) A P electrode 106 which is formed on the P-type GaN layer 104.

(8) An insulating protective layer 107, which is formed on the surface of the bare light emitting diode for protecting the light emitting diode.

In the above light-emitting diodes, the tunneling junction is formed by simultaneously doping N/P in the GaN barrier layer of the MQW structure, which can effectively improve the transmission and diffusion of holes and electrons in the entire MQW region, thereby widening the light-emitting region of the MQW and improving the holes. The probability of recombination with electrons, thus, can significantly improve the luminous efficiency of the LED. In addition, in the MQW structure, the barrier layer is doped with N/P in various forms, and the design space is large, and the luminous efficiency of the LED can be fully optimized.

The preferred embodiments of the present invention have been described above, and it should be understood that those skilled in the art can modify the invention described herein while still achieving the benefits of the present invention. Therefore, the above description should be understood as being widely recognized by those skilled in the art, and is not intended to limit the invention, and any modifications made in accordance with the invention are within the scope of the invention.

Claims

A light emitting diode comprising: a substrate, a buffer layer, an N-type GaN layer, an MQW light-emitting layer, and a P-type GaN layer, wherein the MQW light-emitting layer is alternately stacked by periodic wells/barriers, and the well layer is In x A Ga 1-x N layer, which is a N/P doped GaN layer.
The light emitting diode according to claim 1, wherein the number of periods of the MQW light emitting layer is 2 to 100.
The light emitting diode according to claim 1, wherein x of the In composition in said In x Ga 1-x N well layer ranges from 0 < x < 1.
The light emitting diode according to claim 1, wherein the number of the N/P-doped GaN barrier layers is: 1≤numbers ≤MQW periods.
The light emitting diode according to claim 1, wherein the N/P doping in the GaN barrier layer is uniform doping, non-uniform doping or delta doping, which is realized by controlling a switch of the MO source MFC.
The light emitting diode according to claim 5, wherein the N/P doping source in the GaN barrier layer is SiH 4 and CP 2 Mg, respectively.
The light emitting diode according to claim 1, wherein the number of N/P doping periods in the GaN barrier layer is from 1 to 100.
The light emitting diode according to claim 1, wherein the N/P doped region in the GaN barrier layer is required to be inside the barrier layer, and the both sides of the barrier layer near the well layer are undoped, and the non-doped GaN thickness is ≥ 5 nm to prevent diffusion of Si/Mg into the well layer in the In barrier layer and the barrier layer in the well layer.
The light emitting diode according to claim 1, wherein a doping concentration of N/P in the GaN barrier layer is required to be ≤ a doping concentration of N/P in the N-type GaN layer/P-type GaN layer, in a range of 1 ×10 16 to 1 × 10 21 cm -3 .
The light emitting diode according to claim 1, wherein the concentration of N doping in the GaN barrier layer is gradually decreased as it approaches the P-type GaN layer, and the P doping concentration is gradually decreased as it approaches the N-type GaN layer.