HEMT epitaxial structure and preparation method thereof

Abstract

The invention discloses a HEMT epitaxial structure and a preparation method thereof, and belongs to the technical field of the semiconductor optoelectronics. Component of A1 in an AlGaN buffer layer is gradually reduced along a laminating direction of the AlGaN buffer layer, so that the quality of the AlGaN buffer layer on an AlN nucleating layer is comparatively good; the AlGaN buffer layer comprises n AlGaN buffer sub-layers orderly laminated on the AlN nucleating layer, each AlGaN buffer sub-layer is set to include a bottom structure and multiple cone convexes arranged on the bottom structure, so that the n-th AlGaN buffer sub-layer can horizontally grow towards a direction parallel to a first surface when the n-th AlGaN buffer sub-layer gradually and longitudinally grows to a directionfar away from a first surface of the substrate on the bottom structure; partial dislocation defect produced when the n-th Al GaN buffer sub-layer longitudinally grows and the partial dislocation defect produced when the n-th Al GaN buffer sub-layer horizontally grows can be counteracted, the reduction of the defect can improve the crystal quality of the n-th AlGaN buffer sub-layer. The quality ofthe whole AlGaN buffer layer is improved, and then the quality of the GaN layer grown on the AlGaN buffer layer is improved.

Description

technical field [0001] The invention relates to the field of semiconductor optoelectronic technology, in particular to a HEMT epitaxial structure and a preparation method thereof. Background technique [0002] HEMT (High Electron Mobility Transistor, High Electron Mobility Transistor) is a heterojunction field effect transistor, which is widely used in various electrical appliances. The HEMT epitaxial structure is the basis for preparing HEMT devices. The current HEMT epitaxial structure includes a substrate and an AlN nucleation layer, an AlGaN buffer layer, a GaN layer, an AlGaN barrier layer, and a GaN capping layer grown on the substrate in sequence. The bottom can be silicon carbide substrate, sapphire substrate or single crystal silicon substrate. [0003] However, due to the large lattice mismatch between the GaN layer and the silicon carbide substrate, sapphire substrate or single crystal silicon substrate, even if there is an AlN nucleation layer and an AlGaN buffe...

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Problems solved by technology

[0003] However, due to the large lattice mismatch between the GaN layer and the silicon carbide substrate, sapphire substrate or single crystal silicon substrate, even if there is an AlN nucleation layer and an AlGaN buffer sublayer between the substrate and the GaN layer Playing a buffer role, the crystal quality of the GaN layer finally grown is not good enough, which affects the quality of HEMT

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