金属-绝缘体-半导体（MIS）结构可改善传统高电子迁移率晶体管（HEMT）栅极漏电大和正向栅耐压低的缺点，尤其适用于超薄势垒增强型GaN基功率开关器件。由于AlGaN/GaN的强压电极化效应，MIS-HEMT栅介质应力与界面态之间存在复杂的耦合作用，其界面态会引起阈值电压不稳定、动态导通电阻增大和界面漏电的问题。本项目将对AlGaN/GaN MIS-HEMT栅介质应力与界面态的耦合作用进行深入研究，通过改变沉积工艺参数来调控栅介质应力、调整势垒层的厚度和Al组份来改变异质结的压电极化效果，采用变温和光照辅助的电学测试对基于GaN和Si两种衬底的MIS-HEMT的界面陷阱和电荷以及沟道载流子等电学特性进行定量表征和比较分析，揭示栅介质应力与界面态耦合作用的内在机理，探寻利用该耦合作用调控器件沟道导电性和阈值电压的新方法，为发展高性能增强型GaN基功率开关器件提供理论基础和技术指导。

Metal-insulator-semiconductor (MIS) structure is highly preferred over Schottky-gate structure especially for enhancement-mode AlGaN/GaN high electron mobility transistors (HEMTs), owing to its ability to suppress gate leakage and enlarge gate swing. However, high density trap states at the interface could lead to threshold voltage instability, high dynamic on-resistance and surface leakage current. Additionally complicated coupling effects exist between interface states and gate dielectric induced stress due to strong piezoelectric polarization effect in AlGaN/GaN structure. We propose to study the coupling effects, aiming to reveal its mechanisms and develop approaches to manipulate threshold voltage and conductivity of two-dimensional electron gas (2DEG) channel. We attempt to uncover the underlying mechanisms by depositing the silicon nitride dielectric with various residual stresses, adjusting the thickness and Al composition of the AlGaN barrier to modulate piezoelectric effect, carrying out detailed electrical characterization at various temperatures and with light illumination, quantitatively and comparatively analyzing interface traps, interface charges and carriers in the 2DEG channel on both GaN and Si substrates. The results will provide fundamental foundation and guidance for the development of high performance enhancement-mode GaN-based high-power switching devices.