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

Normally-off HEMTs have been fabricated with regrown p-GaN gate and SiN
_x
passivation by Low-pressure chemical vapor deposition (LPCVD) using an AlN pre-layer, featuring a high-temperature passivation-first technique with no incompatibility issues. Through careful surface treatments, high-quality interfaces (regrown p-GaN/AlGaN and SiN
_x
/ AlGaN), 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 μA/mm @ V
_GS
= 5 V, a positive threshold voltage of +1.7 V @ I
_DS
= 10 μA/mm with a high saturation current of 435 mA/mm, a high I
_on
/I
_off
ratio of 5 × 10
¹⁰
, and a low R
_on,d
/R
_on,s
ratio of 1.5. The as-developed technique with the LPCVD SiN
_x
passivation and p-GaN gate regrowth may provide a way to enhance the performance of p-GaN E-HEMTs.