Degradation mechanism of enhancement-mode AlGaN/GaN HEMTs using fluorine ion implantation under the on-state gate overdrive stress

• Published in: Chinese physics B 2015, Vol.24 (1), p.444-448
• Main Author: 孙伟伟 郑雪峰 范爽 王冲 杜鸣 张凯 陈伟伟 曹艳荣 毛维 马晓华 张进成 郝跃
• Format: Article
• Language: English
• Subjects: AlGaN; Aluminum gallium nitrides; Barrier layers; Degradation; Fluorine; Gates; HEMT器件; High electron mobility transistors; Semiconductor devices; Stresses; 动应力; 增强型; 栅极; 氟离子; 离子注入技术; 降解机理
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/24/1/017303

The degradation mechanism of enhancement-mode Al Ga N/Ga N high electron mobility transistors（HEMTs） fabricated by fluorine plasma ion implantation technology is one major concern of HEMT＇s reliability. It is observed that the threshold voltage shows a significant negative shift during the typical long-term on-state gate overdrive stress. The degradation does not originate from the presence of as-grown traps in the Al Ga N barrier layer or the generated traps during fluorine ion implantation process. By comparing the relationships between the shift of threshold voltage and the cumulative injected electrons under different stress conditions, a good agreement is observed. It provides direct experimental evidence to support the impact ionization physical model, in which the degradation of E-mode HEMTs under gate overdrive stress can be explained by the ionization of fluorine ions in the Al Ga N barrier layer by electrons injected from 2DEG channel.Furthermore, our results show that there are few new traps generated in the Al Ga N barrier layer during the gate overdrive stress, and the ionized fluorine ions cannot recapture the electrons.