Effect of Facile p-Doping on Electrical and Optoelectronic Characteristics of Ambipolar WSe(2) Field-Effect Transistors

We investigated the electrical and optoelectronic characteristics of ambipolar WSe(2) field-effect transistors (FETs) via facile p-doping process during the thermal annealing in ambient. Through this annealing, the oxygen molecules were successfully doped into the WSe(2) surface, which ensured higher p-type conductivity and the shift of the transfer curve to the positive gate voltage direction. Besides, considerably improved photoswitching response characteristics of ambipolar WSe(2) FETs were achieved by the annealing in ambient. To explore the origin of the changes in electrical and optoelectronic properties, the analyses via X-ray photoelectron, Raman, and photoluminescence spectroscopies were performed. From these analyses, it turned out that WO(3) layers formed by the annealing in ambient introduced p-doping to ambipolar WSe(2) FETs, and disorders originated from the WO(3)/WSe(2) interfaces acted as non-radiative recombination sites, leading to significantly improved photoswitching response time characteristics. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s11671-019-3137-1) contains supplementary material, which is available to authorized users.