Ultra-thin AlGaN/GaN HFET with a high breakdown voltage on sapphire substrates
Zhiwen Liang, Hanghai Du, Ye Yuan, Qi Wang, Junjie Kang, Hong Zhou, Jincheng Zhang, Yue Hao, Xinqiang Wang, Guoyi Zhang
Abstract
In this Letter, an ultra-thin AlGaN/GaN heterostructure field effect transistor (HFET) with a total thickness of ∼200 nm was fabricated on sapphire substrates by combing physical vapor deposition and metal organic chemical vapor deposition growth methods. Thanks to the absence of a conventional semi-insulating thick GaN buffer by taking advantage of an ex situ sputtered AlN nucleation layer, we achieved a profound soft breakdown voltage of 1700 V accompanied by a 12.5 Ω·mm on-resistance and a low off-state leakage of 0.1 μA/mm in such ultra-thin HFET devices. Our work demonstrates an alternative strategy to fabricate GaN based power devices with high breakdown voltage and low cost.