An Extensive Negative Gate Bias Stress Degradation Mechanism in GaN MIS-HEMTs for Aerospace Applications

In recent years, GaN HEMT has become one of the most ideal devices for its low on-state resistance and high breakdown voltage. Compared with other HEMT structures, GaN MIS HEMT is recognized as one of the most attractive candidates to replace silicon-based high-power devices in the aerospace industry because of their excellent temperature tolerance. Therefore, this study investigates how a wide temperature range of 77–393 K influences the degradation mechanism of negative gate bias stress (NGBS) in GaN MIS-HEMTs. The threshold voltage shift for GaN MIS-HEMTs’ NGBS is very distinctive both under cryogenic temperature and high temperature. Typically, as the temperature rises from 77 to 303 K, the positive shift of threshold voltage also increases due to electron trapping in the Si
₃
N
₄
bulk layer and at the Si
₃
N
₄
/AlGaN interface. However, from 303 to 393 K, the opposite behavior of the threshold voltage shift is observed due to additional hole trapping in Si
₃
N
₄
from ionization impact, which can be verified from its stress data in Silvaco TCAD simulation and its recovery duration as well. In addition, a thicker Si
₃
N
₄
layer device is produced to clarify the NGBS model. Thus, this study proposes an extensive NGBS model from 77 to 393 K to verify the abnormal degradation phenomenon in GaN MIS-HEMTs.