A Diamond:H/WO3 Metal–Oxide–Semiconductor Field-Effect Transistor

A p-type Diamond:H/WO 3 metal-oxide-semiconductor field-effect transistor (MOSFET) based on surface transfer doping is demonstrated. Using a low-temperature ALD-grown HfO 2 as gate insulator, the Diamond:H/WO 3 MOSFETs show excellent output characteristics, gate-controllable 2-D hole gas, and low gate leakage current. Long-channel FETs exhibit improved subthreshold behavior but reduced transconductance with respect to short-channel devices. An observed WO 3 -thickness-dependent threshold voltage is consistent with enhanced surface transfer doping as the WO 3 layer is thinned down. Low-temperature measurements suggest a significantly lower mobility than expected in this material system. This illustrates the challenge of maintaining high TMO quality during device fabrication.