Performance and VTH Stability in E-Mode GaN Fully Recessed MIS-FETs and Partially Recessed MIS-HEMTs With LPCVD-SiNx/PECVD-SiNx Gate Dielectric Stack

In this paper, we carried out a systematic comparison between the enhancement-mode GaN-based fully recessed metal-insulator-semiconductor field-effect transistors (MIS-FETs) and partially recessed MIS-high-electron-mobility transistors (MIS-HEMTs) with the same gate dielectric stack (LPCVD-SiN
_x
/PECVD-SiN
_x
) that has delivered promising long-term reliability and stability. Despite a moderately larger on-resistance (R
_ON
), the MIS-FETs deliver superior V
_TH
uniformity and thermal stability. Under long-term gate bias stress, both the MIS-HEMT and MIS-FET deliver similar small positive-bias temperature instability, while the negative-bias temperature instability of the MIS-HEMT is much larger than that of MIS-FET. The MIS-FET also delivers a higher V
_TH
stability than the MIS-HEMT under dynamic gate bias stress. It is suggested that the differences in V
_TH
stability mainly originate from the different spatial separation between the trap states and the conducting channel, with it being larger in MIS-HEMT than in MIS-FET.