Threshold Voltage Instability of Diamond Metal–Oxide–Semiconductor Field‐Effect Transistors Based on 2D Hole Gas

Abstract

Recent marked advances in diamond metal–oxide–semiconductor field‐effect transistors (MOSFETs) have raised the issue of gate reliability. Herein, the threshold voltage stability of MOSFETs based on hydrogen‐terminated diamond surface conductivity is examined. The electrical output characteristic curves are characterized by cyclic gate sweeping from reverse to forward gate bias (RF) and from forward to reverse gate bias (FR), respectively. The characteristics of drain current versus drain voltage are affected by the gate bias sweeping direction. Marked hysteresis is also observed in the transfer curves for the RF and FR gate sweeping. The different gate sweeping directions induce threshold voltage variation and hole mobility change. The facts that 1) no extra interface states are generated due to gate sweeping and 2) the trapped charge density depends on the gate oxide thickness, reveal that charge trapping occurs at the border of the gate oxide.