Enhanced voltage blocking ability of AlGaN/GaN heterojunction FETs-on-Si by eliminating leakage path introduced by low-temperature-AlN interlayers

Abstract

In this work, we demonstrate an enhanced voltage-blocking ability for GaN-on-Si epitaxial structure with the novel feature of combined Mg-doped-GaN/low-temperature-AlN (LT-AlN) interlayers in the buffer. With an optimized Mg-doping level, such combined interlayers can eliminate the original leakage path at the LT-AlN/GaN interface due to the interfacial roughening effect caused by the Mg doping. As a result, for AlGaN/GaN heterojunction FETs (HFETs) fabricated on such epitaxial structure (template), its off-state leakage current could be reduced by 1–2 orders of magnitude and its breakdown voltage could be remarkably raise to 252%. Although, the Mg-doped-GaN interlayer would cause a little degradation on device on-state performance, such as 6.6% increase of on-resistance, its contribution on improving device’s voltage-blocking ability and reducing its off-state power dissipation outweighs the drawbacks.