Capacitance–voltage characteristics of Pt/hBN/WSe2 metal–insulator–semiconductor capacitor doped by charge-transfer process

Abstract

Metal–insulator–semiconductor (MIS) capacitors composed of low-dimensional van der Waals (vdW) materials are of fundamental interest for understanding carrier transport properties at the atomic scale. Herein, we fabricated a Pt/hBN/WSe2 MIS low-dimensional capacitor, followed by UV/ozone-induced oxidation to form a WOX layer, which is an electron-withdrawing agent. Capacitance–voltage (C–V) characteristics before and after p-doping of the WSe2 layer were compared for different durations of UV/ozone treatments. The C–V behaviors in the pristine condition exhibited ambipolar transport characteristics at both high and low frequencies because of co-existence of electron and hole carriers, which are advantageous for next-generation complementary MIS architectures. When WSe2 was p-doped, a typical p-type C–V curve with a high-frequency inversion region was observed, because the minority carriers (electrons) were unavailable. The frequency dispersions and ratios of the current to pristine hole concentrations as well as holes to electrons at different p-doping concentrations were analyzed. Finally, the controllability of the charge-transfer doping method was confirmed by chemically removing the WOX layer. The understanding of controllable and damage-free doping mechanisms in ambipolar vdW semiconductors is expected to help enhance electronic device performances at the atomic thickness.