Gallium nitride transistor epitaxial structure capable of improving surface electron concentration and preparation method thereof

Abstract

The invention discloses a gallium nitride transistor epitaxial structure capable of improving surface electron concentration and a preparation method thereof. The method comprises the following steps of sequentially depositing a plurality of ScAlN layers with gradually-changed components on a heterogeneous substrate as a buffer layer, carrying out the high-temperature recrystallization of the buffer layer, forming a nucleation center, carrying out the three-dimensional growth of a GaN material, and carrying out the combined growth of three-dimensional to two-dimensional growth, forming abottom layer structure and growing epitaxial structures such as a high-resistance GaN material, a GaN channel layer, an ScAlN barrier layer and a GaN cap layer on the bottom layer structure. The method has the beneficial effects that the bottom layer of the sample adopts the lattice-matched ScAlN buffer layer for transition, so that the GaN body material layer is higher in crystal quality and smoother in surface; meanwhile, before the ScAlN material barrier layer is grown, the buffer layer at the bottom layer can perform secondary stress release, so that the whole epitaxial structure is in a zero stress state, the interface quality among the layers is improved, and the transistor has higher surface electron concentration under the GaN / ScAlN polarization effect and is suitable for being applied to acousto-optic devices.

Description

technical field [0001] The invention relates to the field of semiconductor material technology, in particular to an epitaxial structure of a high surface electron concentration transistor and a preparation method thereof. Background technique [0002] With the rapid development of third-generation semiconductor materials and devices represented by GaN and SiC, the demand for high-quality GaN thin film materials is becoming more and more urgent. Because the GaN single crystal heterogeneous substrate is relatively expensive, the current mainstream GaN thin film materials are all obtained by heteroepitaxy method on the heterogeneous substrate. The dislocation density of the crystal quality of this thin film material is between 10 8 cm -2 There is still a lot of room for improvement. At present, the mainstream method of heteroepitaxy is the two-step growth method, and (Al)GaN material is selected as the buffer layer, which is used as the transition between the heterogeneous su...

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Problems solved by technology

However, this type of material has limited lattice matching and stress matching effects on subsequent GaN thick films, which restricts the growth of high-quality and low-stress GaN films in the later stage, and has a great impact on the development of high-performance GaN devices that require thicker films. Especially two-dimensional devices with high interface requirements that use polarization effects to generate high-concentration electrons and high mobility

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