卤素杂质对增强型AlGaN/GaN高电子迁移率晶体管性能的影响机理研究

AlGaN/GaN high electron mobility transistors (HEMTs) have been considered as promising candidates for microwave power amplifiers and high speed digital circuits. In these applications, however, enhancement-mode (E-mode) AlGaN/GaN HEMTs are highly desirable to simplify circuit configurations, reduce system costs and guarantee safe operations. Ion implantation and etching technique are usually carried out to fabricate E-mode AlGaN/GaN HEMTs, which lead to the inclusion of halogen impurities in these devices. However, the impacting mechanism of halogen impurities on the performance of E-mode AlGaN/GaN HEMTs is still yet to be essentially addressed. In this project, we plan to investigate the formation, structures and electronic properties of AlGaN containing halogens by first-principles calculations. On this basis, we will simulate the electrical properties and electrical-stress-induced degradations of E-mode AlGaN/GaN HEMTs containing halogen impurities. By combining the above-mentioned researches, we will illuminate the impacting mechanism of halogens on the performance of E-mode AlGaN/GaN HEMTs. The results will not only enrich the impurity theory of halogens in E-mode AlGaN/GaN HEMTs, but also be practically of interest for the performance-improvement of E-mode AlGaN/GaN HEMTs by the regulation of halogen impurities.

增强型AlGaN/GaN高电子迁移率晶体管（HEMT）对于简化电路结构、降低成本、提高系统安全性从而深化AlGaN/GaN HEMT在微波功率放大器和高速数字电路中的应用具有重要意义。通过离子注入或刻蚀工艺制备的增强型AlGaN/GaN HEMT中往往含有卤素杂质，而目前卤素杂质对器件性能的影响机理尚不明确。针对这一问题，本项目从第一性原理计算出发，明确卤素杂质的稳态构型及其对AlGaN几何结构及电子结构的影响；基于卤素杂质的稳态构型，通过器件仿真研究卤素杂质对AlGaN/GaN异质结性质及其对AlGaN/GaN HEMT电学性能的影响机理，探究含卤素杂质的增强型AlGaN/GaN HEMT在电应力下的退化机制。研究结果不仅有助于加深人们对增强型AlGaN/GaN HEMT中卤素杂质的认识，而且对于通过调控卤素杂质来提高增强型AlGaN/GaN HEMT的性能具有重要的理论指导意义。

增强型AlGaN/GaN高电子迁移率晶体管（HEMT）对于简化电路结构、降低成本、提高系统安全性从而深化AlGaN/GaN HEMT在微波功率放大器和高速数字电路中的应用具有重要意义。通过离子注入或刻蚀工艺制备的增强型AlGaN/GaN HEMT中往往含有卤素杂质，而目前卤素杂质对器件性能的影响机理尚不明确。.针对以上问题，本项目采用基于第一性原理计算的缺陷计算出发，明确了F杂质和Cl杂质在GaN中的稳定缺陷构型及其基本缺陷性质；以F杂质为例，明确了AlGaN的合金化对F杂质缺陷性质的影响；阐明了AlGaN合金中F杂质与本征缺陷及原生杂质的相互作用情况；并采用细致平衡理论明确了F杂质对AlGaN/GaN HEMT电学性质影响的微观机理。我们的研究结果不仅有助于加深人们对增强型AlGaN/GaN HEMT中卤素杂质的认识，而且对于通过调控卤素杂质来提高增强型AlGaN/GaNHEMT的性能具有重要的理论指导意义。