SiC衬底上Ga2O3厚膜外延中缺陷调控机理研究

As a new type of wide bandgap semiconductor material, gallium oxide (Ga2O3) has shown great potential in the field of power devices. However, the developments of Ga2O3 in the application of power devices are severely restricted by the absence of p-type conductivity and lower thermal conductivity. The Ga2O3/SiC heterostructure is expected to solve the above problems. Based on the demand of high-quality Ga2O3/SiC heterostructures for Ga2O3/SiC power devices, the effects of defects on the characteristics of Ga2O3/SiC heterojunction and the control mechanism of defects in Ga2O3 thick heteroepitaxial films grown on SiC substrate will be studied. Meanwhile, the generation and transformation model of defects in β-Ga2O3/4H-SiC heterojunction interface and thick β-Ga2O3 heteroepitaxy layers will be established and the generation and transformation mechanism of defects will be analyzed via characterization of the heterojunction and heteroepitaxy layer. Based on the generation and transformation mechanism, the growth process of thick β-Ga2O3 heteroepitaxy films on 4H-SiC will be further optimized and thick β-Ga2O3 heteroepitaxy layer of high quality will be achieved which meets the materials requirements of Ga2O3 power device applications.

作为一种新型的宽禁带半导体材料，氧化镓在功率器件领域展现出了巨大的应用潜力。然而，p型半导体材料的缺乏和较低的热导率严重地制约着Ga2O3在功率器件应用方向的发展。Ga2O3/SiC 异质结构有望解决上述问题。本项目基于Ga2O3/SiC功率器件对高质量Ga2O3/SiC异质结的需求，针对缺陷对异质结特性的影响及SiC衬底上Ga2O3厚膜外延中缺陷调控机制这两个关键问题开展研究。拟通过理论和实验研究，建立异质厚膜外延中缺陷的产生和转化模型，揭示异质结界面及材料中缺陷的产生和转化机理，提出4H-SiC衬底上厚膜β-Ga2O3外延材料缺陷的控制方法；研究缺陷对Ga2O3/SiC 异质结电学及热学特性的影响，并根据异质结特性的测试结果，进一步优化β-Ga2O3异质外延材料生长工艺，最终制备出高性能的4H-SiC基厚膜β-Ga2O3外延材料，满足Ga2O3功率器件应用需求。

本项目以功率器件的应用为研究背景，围绕高质量Ga2O3/SiC异质结制备开展了多方面的研究，主要内容及成果如下：建立了基于低压化学气相淀积系统的SiC衬底上Ga2O3外延生长工艺，结合外延材料的表征手段系统地研究了工艺参数、衬底偏角度等对SiC上Ga2O3外延薄膜晶体结构、表面形貌、光学等特性的影响，并对SiC衬底上Ga2O3外延薄膜生长模式进行了研究。建立了β- Ga2O3/4H-SiC异质结界面的模型，结合第一性原理计算和异质结界面的表征对β-Ga2O3/4H-SiC异质结界面的形成能、结合能、键合机制等电子特性进行了研究。建立并优化了Ga2O3外延薄膜的缺陷腐蚀工艺，研究了工艺参数对SiC衬底上Ga2O3外延薄膜缺陷的影响规律。通过第一性原理计算，研究了O和Ga空位的模型及其对Ga2O3晶体电子特性的影响。对β-Ga2O3/SiC异质结热学特性进行了仿真研究，分析SiC基β-Ga2O3器件结温的改善方案。项目累计发表与研究内容相关的学术论文13篇，申请并授权中国发明专利3项，培养研究生3名。