Ultraviolet LED epitaxial structure and preparation method thereof

Abstract

The invention provides an ultraviolet LED epitaxial structure and a preparation method thereof, and relates to the light-emitting diode technical field. The epitaxial structure comprises a substrate,a first AlN layer, a second AlN layer, an AlN / AlGaN superlattice stress release layer, an N-type AlcGa1-cN ohmic contact layer and an AlxGa1-xN / AlyGa1-yN multi-quantum well active region, wherein theAlN / AlGaN superlattice stress release layer at least comprises a first superlattice and a second superlattice, the AlN / AlGaN superlattice stress release layer can effectively relieve the strain between the second AlN layer and the N-type AlcGa1-cN ohmic contact layer, and the gradually changed Al component in the superlattice can reduce the dislocation density and gradually release the stress caused by lattice mismatch, so that the crack-free and high-quality ultraviolet LED epitaxial structure is obtained, the output power of a deep ultraviolet LED is improved, and the phenomenon of deep ultraviolet whitening is improved.

Description

technical field [0001] The present invention relates to the technical field of light-emitting diodes, and more particularly, to an epitaxial structure of an ultraviolet LED (Light-Emitting Diode, light-emitting diode) and a preparation method thereof. Background technique [0002] In recent years, with the characteristics of safety, small size, environmental protection, high efficiency, and low energy consumption, ultraviolet LED light sources have gradually replaced traditional mercury lamp light sources, and their market share has increased year by year with great potential. The application of ultraviolet LEDs in the field of sterilization and disinfection has received unprecedented attention and attention. [0003] Usually, in the process of manufacturing an ultraviolet LED, an AlN buffer layer and an AlGaN material are sequentially grown on the surface of the substrate. The AlGaN material is located on the side of the AlN buffer layer away from the substrate, and the mo...

AI Technical Summary

Problems solved by technology

The AlGaN material is located on the side of the AlN buffer layer away from the substrate, and the most commonly used substrate is sapphire (Al 2 o 3 ), the large lattice mismatch and thermal mismatch between the AlN buffer layer and the sapphire substrate will introduce a large number of dislocations, and will also lead to a large growth stress of the epitaxial layer, which is easy to crack during the cooling process

Moreover, after the AlN buffer layer is grown, AlGaN materials such as non-doped AlGaN layer or N-type AlGaN ohmic contact layer are grown immediately. Due to the difference in lattice constant, the dislocation density will further increase, and a large number of threading dislocations will proliferate upwards. , so that defects appear in AlGaN and it is easy to trap electrons and holes, resulting in the phenomenon of white light

In addition, the high stress in the growth process of AlGaN will also lead to cracks on the surface, especially the edges, which will reduce the usable area and reduce the output rate.

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