Selective Surface Modification and Layer Thinning of MoS₂ via Ultraviolet-Light Irradiation in an Ionic Solution: Implications for Multifunctional Nanoelectronic Devices

The electrical properties of transition-metal dichalcogenides (TMDs), such as MoS 2, are highly dependent on carrier doping and layer thickness. The ability to selectively control these two critical characteristics is of great importance in order to develop TMD-based multifunctional nanoelectronic device applications, which remains challenging. Here, we report a strategy for controllable surface modification and layer thinning of MoS 2 via ultraviolet (UV)-light irradiation in a silver ionic (Ag + ) solution environment. The results show that, by adjustment of the UV irradiation time, nanostructured Ag ultrathin films (∼2.9 nm) are uniformly deposited on monolayer MoS 2 and can lead to a controllable p-type doping effect, while the thickness of MoS 2 from few-layer to thick-layer could be thinned to the atomic monolayer limit. Both Ag nanostructure deposition and layer thinning have been evidenced to initiate from the edges of MoS 2, independent of the edge type, thus revealing a unique UV-light-assisted defect-induced surface modification and layer-thinning mechanism. Overall, this study provides a simple methodology for the selective control of doping and layer thickness in TMDs, paving the way for developing multifunctional nanoelectronics and integrated optoelectronics.