β-Ga₂O₃ heterojunction field-effect transistors prepared via UV laser-assisted p-doping of two-dimensional WSe₂

The device applications of β-Ga₂O₃ semiconductors are limited by the absence of effective acceptors to form β-Ga₂O₃ p-n homojunctions. Herein, a WSe₂/β-Ga₂O₃ p-n heterojunction formed by van der Waals interaction was exposed to an area-selective He-Cd UV laser (wavelength: 325 nm), increasing the hole carrier concentrations in the ambipolar WSe₂ layer via the self-limited formation of WO_X with a high electron affinity. The device parameters (on-resistance, on/off current ratio, and ideality factor) of the WSe₂/β-Ga₂O₃ heterojunction p-n diode were systematically evaluated under UV laser treatment of different durations; an ideality factor of as low as 1.2 was obtained after 600 s. A β-Ga₂O₃ junction field-effect transistor (JFET) with a p-WSe₂ heterojunction top-gate exhibited excellent transport characteristics, including a lower subthreshold swing, higher on/off output ratio, and improved field-effect carrier mobility than pristine β-Ga₂O₃ heterojunction FETs. Heterostructure formation by the introduction of two-dimensional p-WSe₂ is an innovative method to demonstrate Ga₂O₃-based p-n diodes and JFETs, which can advance the applications of ultra-wide bandgap β-Ga₂O₃ electronic and optoelectronic devices.