HEMT epitaxial structure and preparation method thereof

Abstract

The invention discloses an HEMT epitaxial structure and a preparation method thereof, belonging to the technical field of semiconductor optoelectronics. An AlGaN buffer layer is configured to comprisean AlGaN underlayer structure and a plurality of conical protrusions arranged on the AlGaN underlayer structure, and a GaN layer grows on the AlGaN underlayer structure; due to the presence of the plurality of conical protrusions, when the GaN layer grows longitudinally in a direction away from the first surface of the substrate gradually on the AlGaN underlayer structure, the GaN layer simultaneously grows laterally in a direction parallel to the first surface, the dislocation defects generated during the longitudinal growth of part of the GaN layer can offset with the dislocation defects generated during the lateral growth of part of the GaN layer, and thus the growth quality of the GaN layer can be improved. In addition, when the GaN layer grows laterally, the defects such as dislocations inside the GaN layer can also move to the side wall of the GaN layer in the direction parallel to the first surface, so that the dislocation defects moving to the interface between the GaN layer and an AlGaN barrier layer can be reduced, the surface quality of the junction between the GaN layer and the AlGaN barrier layer can be improved, and the quality of the finally obtained HEMT can be further 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 the preparation of 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 stacked 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 ...

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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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