Decoupling of Forward and Reverse Turn-on Threshold Voltages in Schottky-Type p-GaN Gate HEMTs
Junting Chen, Mengyuan Hua, Chengcai Wang, Ling Liu, Lingling Li, Jin Wei, Li Zhang, Zheyang Zheng, Kevin J. Chen
Abstract
In a p-channel field-effect-transistor ( p-FET) bridge HEMT device recently realized on a commercial p-GaN/AlGaN/GaN-on-Si power HEMT epi-wafer, it is revealed that the device's reverse-conduction turn-on voltage ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RT</sub> ) can be effectively decoupled from the forward threshold voltage ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> ) of Schottky-type p-GaN gate HEMTs. Unlike the conventional Schottky-type p-GaN gate HEMTs, of which V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RT</sub> is closely linked to V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> , the p-FET-bridge HEMT enables separate designs of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RT</sub> and V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> so that low-loss reverse conduction and high threshold voltage can be simultaneously realized. In addition, V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RT</sub> can be further reduced by engineering the AlGaN barrier layer, which will also benefit a lower channel sheet resistance without lowering V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> .