8.7 W/mm output power density and 42% power-added-efficiency at 30 GHz for AlGaN/GaN HEMTs using Si-rich SiN passivation interlayer

• Published in: Applied physics letters 2022-01, Vol.120 (5)
• Main Authors: Liu, Jie-Long, Zhu, Jie-Jie, Mi, Min-Han, Zhu, Qing, Liu, Si-Yu, Wang, Peng-Fei, Zhou, Yu-Wei, Zhao, Zi-Yue, Zhou, Jiu-Ding, Zhang, Meng, Wu, Mei, Hou, Bin, Wang, Hong, Yang, Ling, Ma, Xiao-Hua, Hao, Yue
• Format: Article
• Language: English
• Subjects: Aluminum gallium nitrides; Applied physics; Gallium nitrides; High electron mobility transistors; Interlayers; Millimeter waves; Passivity; Photoelectrons
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0080120

In this work, high-performance millimeter-wave AlGaN/GaN structures for high-electron-mobility transistors (HEMTs) are presented using a Si-rich SiN passivation layer. The analysis of transient and x-ray photoelectron spectroscopy measurements revealed that the presence of the Si-rich SiN layer leads to a decrease in the deep-level surface traps by mitigating the formation of Ga–O bonds. This results in a suppressed current collapse from 11% to 5% as well as a decreased knee voltage (Vknee). The current gain cutoff frequency and the maximum oscillation frequency of the devices with the Si-rich SiN layer exhibit the values of 74 and 140 GHz, respectively. Moreover, load-pull measurements at 30 GHz show that the devices containing the Si-rich SiN deliver excellent output power density of 8.7 W/mm at Vds = 28 V and high power-added efficiency up to 48% at Vds = 10 V. The enhanced power performance of HEMTs using Si-rich SiN interlayer passivation is attributed to the reduced Vknee, the suppressed current collapse, and the improved drain current.