Electron and Hole-Doping for Influencing the Electronic Transport Properties of MoS₂ Devices at Room Temperature

In this work, MoS2 flakes were mechanically exfoliated onto oxidized silicon substrates and electrically contacted using electron-beam lithography and physical vapor deposition. The devices were characterized by two-terminal optoelectronic measurements in dark and in the presence of broadband lights at room temperature. The devices were then endowed with more dominant electrons as the doping agent by soaking the samples in 1,2 dichloroethane, while predominant hole doping was made possible using UV ozone treatment. The doping effect in MoS2 by 1,2 dichloroethane is believed to be a result of the substitution of sulfur vacancies by the chlorine atoms. The doping effect by UV ozone is imparted as a result of a redox reaction occurring between the water adlayer on the surface of MoS2 and ozone atoms. We have elaborated on the effect of dopants and broadband lights on the two-terminal electrical performance of the devices. A considerable difference in electrical performance is observed between the two dopants in the presence of broadband lights. Due to the substitutional doping effects, significantly higher currents after doping via 1,2 dichloroethane were observed even at low voltages in the dark. The electrical response is attenuated in the presence of broadband lights after chloride doping.