MESFETs and MOSFETs on hydrogen-terminated diamond surfaces

High-performance MESFETs and MOSFETs have been fabricated on hydrogen-terminated surfaces of homoepitaxial diamond films prepared by chemical vapor deposition (CVD). Both enhancement and depletion-mode MESFETs have been obtained with the best transconductances of 10mS/ mm in enhancement mode and 12mS/mm in depletion mode. Depletion-mode MOSFETs have been also realized with the best transcenductance of 16mS/mm utilizing evaporated SiOx as gate insulator. The dc performance of the devices using the hydrogen-terminated diamond surfaces has been evalu-ated by two-dimensional drift-diffusion device simulations using several models of surface channels on the hydrogen-terminated surfaces. Consequently, a realistic surface-channel model has been obtained. Based on the model, the simulations for self-aligned-1μm-gate devices have been also carried out to predict the operation of smaller diamond devices not realized in diamond at present. Their transconductances exceed 100mS/mm.