Method for epitaxial growth of crack-free high-crystal-quality LED epitaxial layer on metal gallium nitride composite substrate

Abstract

The invention discloses a method for epitaxial growth of a crack-free high-crystal-quality LED epitaxial layer on a metal gallium nitride composite substrate. The method comprises the steps of performing annealing treatment on the metal GaN (gallium nitride) composite substrate firstly in an N<2> atmosphere at a temperature of 750-850 DEG C at reaction chamber pressure of less than 300torr, and enabling a low-temperature GaN stress release layer with a thickness of 100-300 nanometers to be grown at a low speed of 0.2-1.0 micron/h; then enabling a high-temperature non-doped GaN buffer layer with a thickness of 1-2 microns to be grown at a variable speed linearly changed from 1 micron/h to 3 micron/h in an H<2> atmosphere at a temperature of 950-1,050 DEG C; next, enabling an n type GaN layer with a thickness of 1-2 microns to be grown at a constant growth speed; then enabling a multi-period InGaN/GaN multi-quantum-well active region to be grown in the N<2> atmosphere at a temperature of 750-850 DEG C; and next, enabling a p type AlGaN/GaN superlattice electron barrier layer and a p type GaN layer to be grown in the H<2> atmosphere at a temperature of 950-1,000 DEG C. According to the method, by optimizing parameters of carrier gas, growth temperature, growth speed and the like in the initial growth period of the metal substrate, thermal mismatch between the GaN epitaxial layer and the metal substrate can be effectively relieved to prevent decomposition of the GaN; and the high-quality GaN-based LED epitaxial layer is prepared on the metal substrate.

Description

technical field [0001] The invention relates to the technical field of semiconductor optoelectronics, and relates to a method for epitaxially developing an LED epitaxial layer with no cracks and high crystal quality on a metal gallium nitride composite substrate. Background technique [0002] People are paying more and more attention to the heat dissipation of LEDs. This is because the light decay or life of LEDs is directly related to its junction temperature. If the heat dissipation is not good, the junction temperature will be high and the lifespan will be short. Lowering the life by 10°C will prolong the life by 2 times. The relationship between light attenuation and junction temperature ( figure 1 ) can be seen, if the junction temperature can be controlled at 65°C, then the lifetime of its light decay to 70% can be as high as 100,000 hours! This is the lifespan people dream of, but is it really possible? Yes, it's possible to do that if you take care of its thermals...

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Problems solved by technology

However, the thermal conductivity of the sapphire substrate is not very good (about 25W / (m-K) at 100°C)

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