HEMT epitaxial structure and preparation method thereof

Abstract

The invention discloses an HEMT ((High Electron Mobility Transistor) epitaxial structure and a preparation method thereof, belonging to the field of semiconductor photoelectric technology. An AlGaN buffer layer is set to include an AlGaN bottom structure and a plurality of cylindrical bulges arranged on the AlGaN bottom structure. When a GaN layer grows gradually on the AlGaN bottom structure, aninterface is formed between the GaN layer and the outer walls of the cylindrical bulges. In traditional methods, the dislocation generated during the growth of the GaN layer moves towards the interface between the GaN layer and the AlGaN barrier layer, while the interface between the GaN layer and the cylindrical bulges enables part of the dislocation defects formed during the growth of the GaN layer to move to the interface between the GaN layer and the cylindrical bulges. The part of dislocation defects will not move to the interface between the GaN layer and the AlGaN barrier layer, so thatthe dislocation defects moving to the interface between the GaN layer and the AlGaN barrier layer is reduced relatively, the surface quality of the joint between the GaN layer and the AlGaN barrier layer is improved, the quality of the AlGaN barrier layer growing on the GaN layer is better, and the quality of an HEMT finally obtained 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 layer between the substrate and the GaN layer, The crystal quality of the finally grown GaN layer is not good enough due to the buffering effect, which affects the quality of HEMT.

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