Analysis and modeling of the influence of gate leakage current on threshold voltage and subthreshold swing in p-GaN gate AlGaN/GaN high electron mobility transistors

In this paper, the p-GaN gate AlGaN/GaN high electron mobility transistors (HEMTs) with varying combinations of gate metal work function and gate geometry are fabricated and investigate the influence of gate leakage current (IGS) on the threshold voltage (VTH) and subthreshold swing (SS). The unique...

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Bibliographic Details
Published in:Journal of applied physics 2024-04, Vol.135 (14)
Main Authors: Liu, Kai, Wang, Chong, Zhang, Kuo, Ma, Xiaohua, Bai, Junchun, Zheng, Xuefeng, Li, Ang, Hao, Yue
Format: Article
Language:English
Subjects:
Aluminum gallium nitrides
Capacitance
Current leakage
Dividers
Electrons
Field effect transistors
Gallium nitrides
Heterojunctions
High electron mobility transistors
Leakage current
Semiconductor devices
Thermal emission
Threshold voltage
Transistors
Work functions
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Summary:In this paper, the p-GaN gate AlGaN/GaN high electron mobility transistors (HEMTs) with varying combinations of gate metal work function and gate geometry are fabricated and investigate the influence of gate leakage current (IGS) on the threshold voltage (VTH) and subthreshold swing (SS). The unique dependence of VTH and SS on gate geometry for different metals is observed, which is different from traditional field-effect transistors. A novel hybrid physics model, consisting of the traditional capacitance divider model and hole injection model, is proposed to explain this phenomenon, and the results exhibit an excellent agreement with the experimental data. The holes traverse the gate/p-GaN Schottky barrier by thermal emission or tunneling and inject into the p-GaN layer, generating the IGS. Expanding upon the traditional capacitance divider model, a portion of the injected holes accumulate at the p-GaN/AlGaN interface and induce the corresponding electrons at the AlGaN/GaN heterojunction, which promotes channel conduction. Hence, the transfer curves display the correlation between IGS and VTH as well as SS. The results show that high IGS can alleviate the instability of VTH caused by the lithographic overlay error, and simultaneously optimize SS. This work offers a novel perspective for examining the turn-on mechanism of p-GaN HEMTs, thereby contributing to device design.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0200487