JPH0281483A - Gallium nitride-based compound semiconductor light-emitting element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a gallium nitride compound semiconductor light emitting device that emits blue light.

[Prior art]

Conventionally, blue light emitting diodes using GaN-based compound semiconductors are known. The GaN-based compound semiconductor is attracting attention because it has high luminous efficiency due to direct transition, and because it emits blue light, which is one of the three primary colors of light. A light emitting diode using such a GaN-based compound semiconductor is produced by growing an N layer made of an N-conductivity type GaN-based compound semiconductor on a sapphire substrate directly or with a buffer layer made of aluminum nitride interposed therebetween. It has a structure in which one layer made of a GaN-based compound semiconductor of one conductivity type is grown on the N layer.

[Problem to be solved by the invention]

Incidentally, in order to improve the luminance of the light emitting diode described above, it is desirable that the thickness of the NFJ be as thick as possible in order to increase the number of carriers contributing to light emission. or,
In order to obtain a high-quality single-layer crystal, it is desirable that the N layer be thick. On the other hand, in order to make the operating voltage uniform, the thickness of one layer needs to be thin, uniform, and precisely controlled. However, when crystal growth is performed only by the conventional MOVPE method, there is a problem that the crystal growth rate is slow and it takes time to form a thick N layer. On the other hand, N-type GaN and 1-type GaN are sequentially deposited on the sapphire substrate.
There is also a method of growing by halide vapor phase epitaxy, but with halide vapor phase epitaxy, the growth rate is fast and it is difficult to make the thickness of one layer thin and uniform. As a result of repeated research on GaN crystal growth, the present inventors have found that after growing most of the N layer using halide vapor phase epitaxy, the upper layer is grown using thin <MOVPE. It has been found that a single layer with good crystallinity can be grown by the MOVPE method. The present invention was made based on such a conclusion, and its purpose is to improve the manufacturing speed and light emitting characteristics of a light emitting device.

[Means to solve the problem]

The structure of the invention for solving the above problems consists of a sapphire substrate and an N-type gallium nitride compound semiconductor (A I2X G) grown directly or indirectly on the sapphire substrate.
a = -N: N layer consisting of X=O) and ■ type gallium nitride compound semiconductor (Al
xGa1 + - x N ; x = o), and the N layer is a thick first N layer grown by halide vapor phase epitaxy, and an organic layer is formed on the first N layer. It has a thin second N layer grown by gold scrap compound vapor phase epitaxy (MOVPE), and the first layer is grown by organometallic compound vapor phase epitaxy (MOVPE).

【Effect of the invention】

Since most of the N layer is grown by halide vapor phase epitaxy, thick NF31 can be obtained at high speed, and the manufacturing speed of the light emitting device has been improved. Moreover, the second N layer in the upper layer part of the N layer is M
Since it was formed by the OVPE method and one layer was grown thereon by the MOVPE method, the first layer had good crystallinity and its layer thickness was controlled to be uniform. As a result, the light emission characteristics were improved.

【Example】

The present invention will be described below based on specific examples. First Embodiment FIG. 1 is a sectional view showing the structure of a light emitting diode 1 according to a specific embodiment of the present invention. Sapphire substrate 2 whose main surface is the 0 plane ((0001) plane)
was washed with nitric acid and then further washed with acetone. After cleaning and blowing nitrogen gas to soften the rock,
The sapphire substrate 2 was attached to a susceptor of a halide vapor phase growth apparatus. Thereafter, the temperature of the reaction chamber was set to 900°C, and HC1 gas was flowed over the metal Ga placed on the upstream side of the gas flow, and the reaction products of both were GaCj', NH, and carrier gas N, was flowed toward the sapphire substrate 2 heated to 1000°C. The flow rate is GaCl
1 is 10 m1/min, NH, is 1. OA/min, N, is 2.
0117 minutes. The thickness of the first N layer 4 made of N-type GaN grown on the sapphire substrate 2 was 20 mm, and the growth rate was about 1 layer/min. Next, the sapphire substrate 2 on which the first N layer 4 had been grown was taken out from the halide vapor phase epitaxy apparatus and placed on a susceptor in the reaction chamber of the MOVPE apparatus. Then, the sapphire substrate 2 is heated to 1000 t' and H is used as a carrier gas.
7 for 2.5jl! /min, N H, 1.5j! / minute,
Trimethyl gallium (TMG) was supplied at a rate of 20 rnl/min for 12 minutes to form a second N layer 8 made of N-type GaN with a film thickness of about 2 mm. Next, the sapphire substrate 2 is heated to 900°C, and H2 is heated to 2.
51.7 min, NH, 1.511/min, TMG 15
ntl/min, and diethyl zinc (DEZ) was supplied at a rate of 5XIO-' mol/min for 5 minutes to form one layer 5 made of ■-type GaN to a thickness of 1.0 μs. Next, aluminum electrodes 6.7 were deposited on the side walls of the first N layer 4 and the second N layer 8 and on the top surface of the first layer 5 to form a light emitting diode. The first N layer 4 of the light emitting diode 1 thus obtained
．． Microscopic photographs of the cross sections of the second N layer 8 and the first layer 5 and reflection diffraction method using a high-energy electron beam (RIIIEED) revealed that good crystallinity was obtained, respectively. In particular, the first N layer 4 was grown at high speed by halide vapor phase epitaxy, and the second N layer 8 was formed on top of it by precisely growing by MOVPE. The results were better than those grown using only the vapor phase growth method. Furthermore, the emission peak spectrum of this light emitting diode 1 is 480 nm, and the emission intensity (on-axis brightness) is 10 mc.
It was d. Second Embodiment FIG. 2 is a sectional view showing the structure of a light emitting diode 10 according to a second embodiment. In the same manner as in the first embodiment, a sapphire substrate 2 having a 0 principal surface ((0001) plane) was cleaned with nitric acid and then further cleaned with acetone. After cleaning and drying by blowing nitrogen gas, the sapphire substrate 2 was attached to a susceptor of a MOVPE apparatus. Thereafter, the sapphire substrate 2 is heated to 600° C., and H2 is supplied as carrier gas at a rate of 212/min, NH, at a rate of 1.51/min, and trimethylaluminum (TMA) at a rate of 15/min for 6 minutes. A buffer layer 3 made of AIN was formed to a thickness of about 0.1 μs. Thereafter, the first N layer 4. A light emitting diode 10 was created by sequentially forming the second N layer 8.1 layer 5. The first NFJ of the light emitting diode 10 created in this way
4. Microscopic photographs of the cross sections of the second N layer 8 and the first layer 5 and reflection diffraction method (R11 (!BD)) using high-energy electron beams revealed that good crystallinity was obtained in each. The emission peak spectrum of the diode 1 was 480 nm, and the emission intensity (on-axis brightness was 10 mcd). Third Embodiment In this embodiment, the buffer layer 3 of FIG. It was created by the epitaxy method (MBE). After cleaning the sapphire substrate 2 whose main surface is the 0 plane ((0001) plane) in the same manner as in the second embodiment, the sapphire substrate 2 was placed in the MBE apparatus. After that, the sapphire substrate 2 was heated to 500° C. and aluminum was evaporated in nitrogen gas plasma to form a buffer layer 3 made of aluminum nitride (AIN) on the main surface of the sapphire substrate 2. It was formed to a thickness of 500. After that, the first N layer 4. The second N layer 8.1 layer 5. The electrode 6.7
The method for creating is the same as in the first embodiment. The first N layer 4 of the light emitting diode thus obtained.
A microscopic photograph of the cross section of the second N layer 8 and the first layer 5 and a reflection diffraction method using a high-energy electron beam (RIIEHD) revealed that good crystallinity was obtained. Furthermore, the spectrum of the emission peak of this light emitting diode 1 is 480nn+, and the emission intensity (on-axis brightness) is 10mc.
It was 'd. According to the inventors' considerations, in the buffer layer 3 formed by MBE, the growth nuclei of GaN of m1NFjF4 are more uniformly dispersed than in the buffer layer 3 grown by MOVPE. For this purpose, the first N layer 4, the second N layer 8
It is considered that the single crystallinity of the first layer 5 was improved. Further, the buffer layer 3 was polycrystalline because it was formed by MBE at 500° C. on the sapphire substrate 2. In addition, the present inventors have found that when the buffer layer 3 is grown as a polycrystalline layer, the first N layer 4 and the second N layer 3 are
It was also found that layer 8 and layer 1 5 had good single crystallinity. For this reason, it is effective to grow the buffer layer 3 by MBE, and the degree of growth of polycrystalline crystals is from room temperature to -50°C.
0°C is desirable. Further, in order to improve the single crystallinity of the first N layer 4, the second N layer 8, and the first layer 5, the thickness of the buffer layer 3 should be 100 to 100 nm.
0 people is desirable. In the above embodiment, the first N layer 4, the second N layer 8, and the first layer 5 are made of GaN, but they may be made of AIX GaN.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the structure of a light emitting diode according to a specific embodiment of the present invention. FIG. 2 is a block diagram showing the structure of a light emitting diode according to another embodiment. 1゜10 ・Light-emitting diode 2 ・Sapphire substrate buffer layer 4 1st N layer 8 2nd N layer ■ layer Patent applicant: Toyota Gosho Co., Ltd., Nagoya University President, New Technology Development Corporation Representative, Fujitani
Shu 1st

Claims (1)

[Claims] A sapphire substrate; and N grown directly or indirectly on the sapphire substrate.
type of gallium nitride-based compound semiconductor (Al_xGa_1_
−_xN; including X=0), and an I-type gallium nitride compound semiconductor (Al_
xGa_1_-_xN; A thin second N film grown by compound vapor phase epitaxy (MOVPE)
A gallium nitride-based compound semiconductor light emitting device, comprising: a gallium nitride compound semiconductor light emitting device, wherein the I layer is grown by metal organic compound vapor phase epitaxy (MOVPE).