基于第一性原理和实验研究影响AlGaN/GaN异质结电子输运的非本征因素

High electron mobility field effect transistor (HEMT) is becoming the fundamental device for high power, high temperature, and high frequency electronics. The control of defects and stress is one of the keys to its success. This research is to study defects and stress in HEMT using method of first principles quantum molecular dynamics combining with theories and technologies in nonlinear field, modern communication theory, develop a characterization method for defects by process and stress in HEMT using comprehensive index based on time domain characterization analysis etc. It focuses on developing essential and reliable theoretical foundation for designation, fabrication, and characterization technology and modelling technology of HEMT. Therefore, the main work is to study how defects in HEMT caused by fabrication process and degradation process affect on the evolution characteristics of the fine electronic structure via the first principles calculation; to study the influence of the residual stress in the interface caused by process and degradation on the fine structure, to study the influence of the evolution of defects and stress on the device characteristics and reliability; to develop a new method to characterize the GaN HEMT characteristics and reliability for physically understanding device behavior such as the current collapse effect and the negative resistance effect and etc; Finally, Nanochannel Array GaN HEMT will be fabricated, and the physical relationship between fine electronic structure and negative resistance effect and current collapse effect will be studied and discussed.

高电子迁移率场效应晶体管（HEMT）正成为高功率，耐高温和高频电子技术的关键基础器件。而对缺陷和应力的控制是其能得到广泛应用的关键技术之一。本项目拟用第一性原理和分子动力学方法来研究在外场等因素作用下缺陷和应力的演化特征，结合非线性理论和现代通信理论来发展新型基于时序特征的表征缺陷和应力综合指标体系，为发展HEMT模型和表征技术提供必要和可靠的理论依据。即用第一性原理计算HEMT制造工艺过程和使用过程中产生的微观缺陷以及引起的界面处残余应力对精细电子结构影响的演化特征；分析缺陷和应力的演化对器件特性及可靠性的影响；且为深入理解电流崩塌效应、负阻效应等输运特性，我们需要创新发展对GaN基HEMT特性和可靠性的表征方法；最后制备纳米沟道阵列GaN基HEMT，重点研究精细电子结构与负阻效应和电流崩塌效应等之间物理关联的模型和表征方法。

基于GaN晶体管中的量子耦合效应和热电子效应建立了一个关于电流崩塌效应的分析的物理模型。很好地解释了GaN基晶体管中的电流崩塌效应。该模型提供了各个物理参数对源漏电流影响的定量的物理模型，提供了一种优化多个器件的物理参数来改善GaN器件性能的可能。基于双电层效应提出了一种简单描述GaN基器件中二维电子气的机理，定量地解释了二维电子气密度对AlGaN中的Al成分的依赖关系和F离子密度对AlGaN对器件特性的影响。建立了基于量子耦合效应的电场诱导的拉曼谱和光谱漂移影响的物理模型，该模型和实验结果吻合的很好。基于多能谷输运建立GaN器件中kink效应模型，和实验吻合很好。此外也利用蒙特卡洛方法研究了GaN器件能谷间的载流子跃迁对电子输运特性的影响。基于第一性性原理和热电子效应建立了热电子对GaN器件特性影响的物理模型的基础上延展了研究工作。发现相关的机理对PN结，有机半导体器件等的建模工作也有效，并展开了相关扩展工作。此外在基金资助下还开展了关于材料的第一性原理计算和电磁特性计算的工作。