The impact of HfO2 dielectric layers deposited at different temperatures on performance and reliability of hydrogen-terminated single-crystal diamond MOSFETs

Abstract

Gate dielectric plays a critical role in determining the electrical performance and stability of hydrogen-terminated diamond (H-diamond) Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). This work systematically investigates the influence of HfO 2 dielectric layers deposited at varying temperatures (80 °C, 150 °C, 250 °C and 350 °C) on device performance and reliability. HfO 2 films of identical thickness were deposited on hydrogen-terminated single-crystal diamond using atomic layer deposition. Electrical output and transfer characteristics were evaluated through cyclic gate bias sweeps in both positive-to-negative and negative-to-positive directions. Under both sweep directions, the saturation current density and threshold voltage exhibited a clear positive correlation with deposition temperature. The subthreshold swing showed a positive temperature dependence when the gate was swept from negative-to-positive. Notably, the device with HfO 2 deposited at 150 °C demonstrated the optimum overall stability, offering valuable guidance for the development of stable H-diamond high-k dielectric MOSFETs.