LAUSR

In recent years, chemical doping based on the charge-transfer phenomenon has been actively studied for transition-metal dichalcogenide (TMD) materials owing to its simplicity and efficiency. However, these chemical-doping techniques have been controlled mostly in a high-doping-concentration (degenerate) regime, consequently limiting the use of the techniques to TMD devices. Herein we report on the wide-range-controllable p-type doping of WSe2 based on hydrochloric acid (HCl) treatment. The doping concentration was controlled broadly between 1.67 × 1011 cm–2 and 1.32 × 1012 cm–2 by adjusting the concentration of the HCl solution. We then confirmed that the performances of the WSe2-based transistor and photodetector devices were improved (increases in the threshold voltage, field-effect mobility, on-current, and photoresponsivity with the doping concentration). Finally, we alleviated the degradation of the HCl doping effects in air by providing protection from the moisture in the air by using poly(methyl me...