Investigations on Electrical Parameters Degradations of p-GaN HEMTs Under Repetitive UIS Stresses
Sheng Li, Siyang Liu, Chi Zhang, Ningbo Li, Xinyi Tao, Jiaxing Wei, Long Zhang, Weifeng Sun
Abstract
Electrical parameters degradations of p-GaN high-electron-mobility transistors (HEMTs) under repetitive unclamped-inductive-switching (UIS) stresses have been investigated in this article. With the help of the TCAD simulations, the experimental frequency-dependent conductance analyses ( G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> /ω), and the experimental capacitance analyses ( C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> ), it is demonstrated that the trapping effects near the gate region and in the gate to drain access region dominate the degradations. Due to the extremely high-voltage bias during UIS stresses, the trapping of electrons happens near gate region, resulting in the positive shifts of threshold voltage ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ), the degradations of ON-state resistance, the reductions of the gate leakage current, and the reductions of OFF-state leakage current ( I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dss</sub> ). Two experimental methods, the C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> analyses and the G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> /ω analyses, are introduced to characterize the trapping effects in p-GaN HEMT for the first time. Nonetheless, the large current surging during UIS stresses enhances the impact ionization and leads to the increase in I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dss</sub> . The analyses above have been validated by the TCAD simulation successfully. For switching parameters, such as the voltage rises/falls time, which should be considered when designing power electronic systems, the increase in V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> induced by the UIS stresses dominates the changes.