Spatially and Precisely Controlled Large-Scale and Persistent Optical Gating in a TiOx–MoS2 Heterostructure

Optical gating derived from persistent photodoping is a promising technique that can control the transport behavior of two-dimensional (2D) materials through light modulation. The advantage of photoinduced doping is that the doping can be controlled precisely and spatially by tuning the light intensity and position. As most photoinduced doping methods suffer from a low doping level, persistent, strong photodoping was conducted in this study in TiOx–MoS2 heterostructures under ultraviolet (UV) illumination, which precisely controlled the doping to a high level (1.5 × 1013 cm–2) with a trap-mediated mechanism. This mechanism was confirmed by controlling the doping level with various UV pretreatment doses. After photodoping, devices displayed superior mobility, which is a characteristic of the modulation doping used in high-electron-mobility transistors. The modulation doping sites in the inner TiOx layer were far from the channel surface (MoS2); thus, the channel was able to preserve its high-mobility prope...