Impact of Temperature and Interface Traps on Threshold Voltage and Carrier Mobility of Hydrogen-Terminated Diamond MOSFETs

We present a Sentaurus TCAD model calibrated for the hydrogen-terminated diamond p-channel MOSFET reported by Hirama et al. and validated using the published transfer characteristics. We used the calibrated model to analyze threshold voltage (Vth) and effective mobility (μeff) over a temperature range from 300 to 600 K and an interface-trap density range from 1012 to 1016 cm−2·eV−1. The analysis shows three main trends: (i) a drain-bias-dependent shift in Vth that becomes stronger at higher temperatures; (ii) a threshold shift toward more negative values with increasing temperature and interface-trap density, showing a coupled thermal trap effect; and (iii) a mobility response that stays near the phonon-limited regime at low trap densities but degrades rapidly as trap density increases. We extracted compact empirical expressions for ΔVth (T, Dit) and μeff (T, Dit) that reproduce the simulated trends with good accuracy for device-level comparison. The results show that interface-trap control is important to achieve thermally stable, high-performance diamond MOSFETs.