Si (Silicon)-base III nitride epitaxial wafer without microcracks in surface

Abstract

The invention discloses a Si (Silicon)-base III nitride epitaxial wafer without microcracks in surface. The Si-base III nitride epitaxial wafer is characterized by comprising an Si substrate, two AlN (aluminium nitride) nucleating layers, three Al<x>Ga<1-x>N intermediate layers with Al components degreased progressively, an AlGa<1-a>N / AlGa<1-b>N superlattice intermediate layer, two GaN channel layers and three barrier layers sequentially from down to up. The Si-base III nitride epitaxial wafer has the advantages that an Si-base III nitride heterojunction is high in surface quality and does not have micro cracks in comparison with an existing technology; furthermore, the AlGaN intermediate layers with progressively-degreased components of which an average Al component is low in an epitaxial layer structure provided by the invention is adopted to achieve an aim of improving surface appearance, therefore, the influence of a pre-reaction between a metal organic source and an ammonia gas can be reduced beneficially, the crystalline quality of the epitaxial wafer can be improved, and the growth rate of the epitaxial wafer can be improved.

Description

technical field [0001] The invention relates to a Si-based Group III nitride epitaxial sheet without microcracks on the surface, in particular to an epitaxial sheet containing a Group III nitride heterojunction capable of generating two-dimensional electron gas. It belongs to the field of semiconductor technology. Background technique [0002] The heterojunction composed of Group III nitride semiconductor materials, such as GaN and Al(In)GaN, can form a two-dimensional electron gas with high concentration and high electron mobility, which is suitable for the development of microwave power field effect transistor devices. Due to the lack of large-sized homogeneous substrates, currently nitride semiconductor materials are mainly grown on substrates such as silicon carbide, sapphire or Si. [0003] Si and III-nitride epitaxial materials have very serious lattice mismatch and thermal mismatch. For example, the thermal mismatch between (0001) plane GaN and (111) plane Si is 54%,...

AI Technical Summary

Problems solved by technology

Simple use of thick Al a Ga 1-a N / Al b Ga 1-b N superlattice is used as the intermediate layer to grow GaN material, because it is difficult to alleviate the mismatch of lattice constant and thermal expansion coefficient, and it is impossible to suppress the appearance of macroscopic cracks

[0013] When the Al composition difference a-b of the two layers in the superlattice interlayer structure exceeds a certain value, misfit dislocations may be generated at the interface and inside of the superlattice, resulting in strain relaxation, which cannot suppress the appearance of macroscopic cracks

[0014] On the other hand, when a high Al composition is used in the superlattice interlayer structure, there is also the problem that the pre-reaction between the metal-organic source and ammonia is intensified, and the quality of the material growth is reduced.

[0015] In addition, even in the case of combining the composition-decreasing AlGaN interlayer with the Al(Ga)N / GaN superlattice interlayer, there are problems of how to combine and match and what growth conditions to use to obtain improved performance

Images