晶格匹配InAlN/GaN HEMT肖特基栅极泄漏电流的退化机制研究

项目名称： 晶格匹配InAlN/GaN HEMT肖特基栅极泄漏电流的退化机制研究

项目编号： No.61504050

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 无线电电子学、电信技术

项目作者： 闫大为

作者单位： 江南大学

项目金额： 20万元

中文摘要： 凭借优越的材料特性，GaN基HEMTs能输出远大于常规Si LD-MOSFETs和GaAs MESFETs的功率密度，在无线通信和雷达系统中具有重要的应用价值。然而，在长时间大信号工作模式下，GaN HEMTs的肖特基栅极却遭受严重的漏电流退化行为，产生不必要的低频噪音和额外功率损耗。鉴于此，本项目拟在晶格匹配InAlN/GaN外延片上制备与标准器件栅极电学性能相同的肖特基结构，（1）利用步进应力法测试和分析漏电流的退化行为，直接验证传统逆压电模型的正确性；（2）利用EMMI监测退化过程中“热点”(即电流失效点)的产生和演化过程，使用C-AFM分析退化前后“热点”处材料表面结构和电导特性的变化，直接验证新结构缺陷的产生是否为电流退化的直接原因；（3）使用高压、高温和电流应力法制备结构相同而缺陷密度不同的样品，分析缺陷对漏电流输运机制的影响。最终，我们将提出一个唯象栅极漏电流退化模型。

中文关键词： 宽禁带半导体；异质结；HEMT；可靠性

英文摘要： Thanks to their excellent material properties, GaN HEMTs can output much higher power density than conventional Si LD-MOSFETs and GaAS MESFETs , which have important applications in the wireless communication and radar systems. Unfortunately, when they are operated in a long-term large signal mode, the gate leakage current suffers from a significant degradation behavior, giving rise to undesirable low-frequency noise and additional power loss. So, in this project we will fabricate circular Schottky contact structure on lattice-matched InAlN/GaN HEMTs epi-wafer, which is of the same electrical properties with the Schottky gate structure of a standard device, and will (1) identify the validity of the inverse piezoelectric effect for gate leakage current degradation by step-stress measurements; (2) and will monitor the “hot spots” (namely current failure points ) for their occurrence and evolution processes by EMMI, and measure the underlying surface structure and conductance property by C-AFM, indicating that the generation of additional structure defects are directly related with the current degradation; (3) will obtain a series of defective samples by high various methods such as revere bias, high temperature and current stresses, studying the current transport mechanisms before and after degradation. Finally，we will propose a phenomenological model for the gate leakage current degradation.

英文关键词： wide band gap;heterojunction;high electron mobility transistor;Reliability