The impact of interfacial Si contamination on GaN-on-GaN regrowth for high power vertical devices
Kai Fu, Houqiang Fu, Xuguang Deng, Po-Yi Su, Hanxiao Liu, Kevin Hatch, Chi-Yin Cheng, D. C. Messina, Reza Vatan Meidanshahi, Prudhvi Peri, Chen Yang, Tsung-Han Yang, Jossue Montes, Jingan Zhou, Xin Qi, Stephen M. Goodnick, F. A. Ponce, David J. Smith, R. J. Nemanich, Yuji Zhao
Abstract
The development of gallium nitride (GaN) power devices requires a reliable selective-area doping process, which is difficult to achieve because of ongoing challenges associated with the required etch-then-regrow process. The presence of silicon (Si) impurities of unclear physical origin at the GaN regrowth interface has proven to be a major bottleneck. This paper investigates the origin of Si contamination at the epitaxial GaN-on-GaN interface and demonstrates an approach that markedly reduces its impact on device performance. An optimized dry-etching approach combined with UV-ozone and chemical etching is shown to greatly reduce the Si concentration levels at the regrowth interface, and a significant improvement in a reverse leakage current in vertical GaN-based p–n diodes is achieved.