Normally-off HEMTs With Regrown p-GaN Gate and Low-Pressure Chemical Vapor Deposition SiNx Passivation by Using an AIN Pre-Layer

Normally-off HEMTs have been fabricated with regrown p-GaN gate and SiNx passivation by Low-pressure chemical vapor deposition (LPCVD) using an AIN pre-layer, featuring a high-temperature passivation-first technique with no incompatibility issues. Through careful surface treatments, high-quality interfaces (regrown p-GaN/AIGaN and SiNx/ AIGaN), as well as a stable p-GaN contact, can be achieved, enabling a robust gate operation and improved dynamic performance. The as-fabricated device exhibits a low reverse gate leakage of 2 nA/mm @ V-GD = -200 V, a stable forward gate current of 10 mu A/mm @ V-GS = 5 V, a positive threshold voltage of +1.7 V @ /(DS) = 10 mu A/mm with a high saturation current of 435 mA/mm, a high /(on)//(off) ratio of 5 x 10(10), and a low R-on,R-d/R-on,R-s ratio of 1.5. The as-developed technique with the LPCVD SiNx passivation and p-GaN gate regrowth may provide a way to enhance the performance of p-GaN E-HEMTs.