Remote Charge Modulation in WSe2 Transistors via Plasma-Induced Charged Defects in hBN

Abstract

Noninvasive carrier-density modulation is essential for two-dimensional (2D) electronics, where conventional doping often introduces lattice disorder or charged scattering centers near the transport channel. Remote doping offers a route to suppress charged impurity scattering, but commonly requires an additional charge-supply layer separated from the channel by a passive spacer. Here, we demonstrate oxygen-plasma-engineered hexagonal boron nitride (hBN) as both a protective spacer and an electrostatically active remote dopant for tungsten diselenide (WSe2) field-effect transistors (FETs). Oxygen plasma treatment generates donor-like defect states near the hBN surface, enabling n-type modulation of the underlying WSe2 channel while preserving spatial separation between the charged defect states and the transport channel. The plasma-treated hBN exhibits clear electrostatic and optical signatures of defect-state formation, and the WSe2 channel remains structurally intact after treatment. The resulting WSe2 FETs show controllable n-type doping, with the doping density increasing nearly linearly with plasma-treatment time. Moreover, the increased carrier density is accompanied by enhanced mobility without an increase in the charged impurity density, indicating remote charge modulation with suppressed charged impurity scattering. This defect-engineered hBN platform provides a simple and noninvasive strategy for carrier-density engineering in 2D electronic devices.