High-mobility p-channel wide-bandgap transistors based on hydrogen-terminated diamond/hexagonal boron nitride heterostructures

Field-effect transistors made of wide-bandgap semiconductors can operate at high voltages, temperatures and frequencies with low energy losses, and are important for power and high-frequency electronics. However, wide-bandgap p-channel transistors perform poorly compared with n-channel ones, making complimentary circuits difficult to achieve. Hydrogen-terminated diamond is a potential p-type material for such devices, but surface transfer doping—thought to be required to generate conductivity—limits performance because it requires ionized surface acceptors that can lead to hole scattering. Here we show that p-channel wide-bandgap heterojunction field-effect transistors can be created, without surface transfer doping, using a hydrogen-terminated diamond channel and hexagonal boron nitride gate insulator. Despite having a reduced density of surface acceptors, the transistors have a low sheet resistance (1.4 kΩ) and large ON current (1,600 μm mA mm−1) compared with other p-channel wide-bandgap transistors, due to a high room-temperature Hall mobility (680 cm2 V−1 s−1). The transistors also exhibit normally OFF behaviour with an ON/OFF ratio of 108. Wide-bandgap transistors with room-temperature hole mobility of 680 cm2 V−1 s−1 can be created without surface doping using hydrogen-terminated diamond/hexagonal boron nitride heterostructures.