Hybrid Gate p-GaN Power HEMTs Technology for Enhanced V<sub>th</sub> Stability
Chi Zhang, Sheng Li, Siyang Liu, Weihao Lu, Yanfeng Ma, Jiaxing Wei, Long Zhang, Weifeng Sun, Denggui Wang, Jianjun Zhou, Song Bai
Abstract
A novel hybrid gate p-GaN power high-electron-mobility transistor (Hyb-HEMT) technology is proposed in this work to effectively enhance threshold voltage $(V_{th})$ stability without obvious gate leakage current $(I_{gss})$ degradation. In this device concept, gate structure consists of spaced ohmic-type p-GaN metal dots and Schottky-type p-GaN metal. Charge storage effect can be alleviated through a free-carrier “discharge path” induced by ohmic-type p-GaN region, thus enhancing the V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> stability. Surrounding geometry distribution of Schottky-type p-GaN metal can take full advantage of depletion region, ensuring a relatively low I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gss</inf> . It is experimentally demonstrated that activation energy $(E_{A})$ of proposed Hyb-HEMT is only 0.59eV, and such a device can suppress V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</inf> shift within only 0.1V (0.42V for commercial HEMT) under DC drain/gate bias stress and repetitive unclamped-inductive-switching (UIS) stress.