Charge-carrier mobility in hydrogen-terminated diamond field-effect transistors

Diamond field-effect transistors (FETs) have potential applications in power electronics and high-output high-frequency amplifications. In such applications, high charge-carrier mobility is desirable for a reduced loss and high-speed operation. We recently fabricated diamond FETs with a hexagonal-boron-nitride gate dielectric and observed a high mobility above 300 cm 2 V − 1 s − 1. In this study, we identify the scattering mechanism that limits the mobility of our FETs through theoretical calculations. Our calculations reveal that dominant carrier scattering is caused by surface charged impurities with a density of ≈ 1 × 10 12 cm − 2 and suggest that an increase in mobility over 1000 cm 2 V − 1 s − 1 is possible by reducing these impurities.