High performance WSe2 p-MOSFET with intrinsic n-channel based on back-to-back p-n junctions

Abstract

Most of the reported field effect transistors (FETs) in two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) are based on the high power consumption Schottky FETs, in which the switching of current relies on the electrostatic modulation of the Schottky barrier at the metal-TMD contact interfaces. Even worse, they have been often mistakenly referred to as 2D metal-oxide-semiconductor field effect transistors (MOSFETs), which, however, have restricted design rules. Here, we demonstrate a two-dimensional p-MOSFET with an intrinsic n-type WSe2 channel. This MOSFET consists of two back-to-back p-n junctions. With a hexagonal boron nitride van der Waals stacking mask, degenerate p-doping to WSe2 from the oxidized surface can be selectively induced to the contact areas by controlled oxygen plasma, while maintaining the center of the channel intrinsic. Compared to Schottky FETs, outstanding device performances are realized, e.g., low field effect threshold, much reduced subthreshold swing, high on/off ratio exceeding 108, hole mobility as high as 191 cm2 V-1 s−1, and hysteresis-free transfer characteristics.