Synergistic Effect of Negative Bias Instability and Total Ionizing Dose on SiC MOSFETs

Yun Tang,Lei Wang,Xiaowu Cai,Shiping Wang,Bin Dong,Mali Gao,Bo Li,Fazhan Zhao,Jianying Dang,Ruirui Xia,Liqiang Ding,Dongqing Hu,Yuexin Gao

doi:10.1109/tns.2023.3273172

Abstract

In this paper, the synergistic effect of negative gate bias and radiation on SiC Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) is investigated. Under negative gate bias (-5V, -10V, -15V), a slight decrease in the threshold voltage (V th ) of non-irradiated SiC MOSFETs is observed. The variation of trapped-oxide charge (N ot ) and SiC/SiO 2 interface trap charge (N it ) can be obtained through the subthreshold swing and mid-gap voltage method. Although the V th of non-irradiated SiC MOSFETs remains unchanged, significant increases in N it and N ot are observed due to the opposite effect of N ot and N it on V th . This phenomenon is attributed to holes drifting to the interface and tunneling into the oxide layer under the negative gate bias. It is found through the C g -V gs characteristic curves that holes tunneling into the oxide layer are mostly from the channel region. For irradiated SiC MOSFETs, a large number of radiation-induced holes exist in the oxide layer above the channel region and JFET region, resulting in a decrease in V th , which is mainly caused by an increase in N ot .

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