二次外延AlGaN势垒层的增强型p-gate GaN HEMT新结构研究

p-gate GaN-based high electron mobility transistor (p-gate GaN HEMT) is one of the forefront topics in the field of high-speed and high-efficiency power electronics. It is difficult to balance high-conduction characteristic in accessed region and good turn-off capacity in gate region for p-gate devices fabricated by traditional methods. To tackle this issue, this project proposes a scheme for a novel p-gate GaN HEMT structure based on regrown AlGaN barrier layer without the usage of mask, therefore, the requirement of etching process is reduced, and the epitaxy structure of access and gate region can be designed more reasonably to obtain high-performance device characteristics. Starting from the design of epitaxial structure and the modulation of energy band, the project intends to focus on the following researches: (1) the regrown control technology and its physical mechanism aiming at achieving high-conduction characteristics in access region, including the repair of regrown interface defects and the growth behavior of the regrown barrier layer; (2) the suppression methods of defects/interface traps in gate region with multi-interface and its influence on electrical properties aiming at achieving a better turn-off capability, including the behavior of Mg diffusion in p-type layer under high temperature, the optimization of metal-semiconductor contact interface and the mechanism of gate leakage. Ultimately, this project looks forward to realizing e-mode GaN-based power devices with independent intellectual property rights, and superior properties of low on-resistance, high threshold voltage, stable dynamic resistance and threshold voltage as well as large gate voltage swing.

p型栅GaN基增强型高电子迁移率晶体管（p-gate GaN HEMT）是高速高效电力电子器件领域的前沿课题之一。为克服传统方案制备p型栅器件难以兼具高开态导通和栅关断特性等问题，本项目提出基于二次外延AlGaN势垒层的p-gate GaN HEMT新工艺新结构，该方案对刻蚀工艺要求降低，基于无掩膜整面二次外延，可合理设计接入区和栅区外延结构提高器件性能。本项目从外延结构设计和能带调制出发，拟重点开展以下研究：（1）以实现高导通特性为目标的接入区二次外延控制技术和物理机理研究，包括二次外延界面缺陷修复及二次外延势垒层生长行为；（2）以实现良好栅关断能力为目标的栅区多界面系统缺陷/界面态抑制及电学特性研究，包括p型层Mg杂质的高温扩散行为、栅极金半界面优化及栅极漏电行为机制。最终实现低导通电阻、高阈值电压、稳定阈值电压和动态电阻、高栅压摆幅特性的具有自主知识产权的GaN基增强型器件。

氮化镓（GaN）作为第三代半导体的代表，具有优异的材料物理特性，更加适合于下一代电力电子系统对功率开关器件更大功率、更高频率、更小体积和更恶劣工作温度的要求。实现高性能的p-GaN栅增强型HEMT是业界追求的目标，但是也面临着挑战。本项目提出二次外延方案，克服传统刻蚀方案的不足。具体开展了p-GaN栅器件结构设计、栅极结构参数调控及器件工作机理分析，并进行了二次外延界面控制及生长行为研究，基于二次外延方案及AlGaN薄势垒层结构和AlN插入层技术等，获得了高阈值电压和良好导通能力的GaN增强型器件，研究了器件中栅界面缺陷的提取及抑制方法，同时也评价了栅极构型对器件栅漏电行为的影响，并基于自主搭建的测试平台评估了不同应力模式下p型栅器件动态阈值电压和动态电阻稳定性。本项目提出的二次外延技术和器件结构，为开发高性能增强型GaN器件提供了一种可行方案。在本项目资助下研究成果发表论文12篇，其中SCI论文10篇，包括权威期刊论文IEEE TED、ASS、JAC、JCG等，以及国际顶级会议论文IEEE ISPSD，并申请（含授权）中国发明专利8项以及美国专利2项。