Encapsulation of a Monolayer WSe Phototransistor with Hydrothermally Grown ZnO Nanorods.

Transition metal dichalcogenides (TMDCs) are promising two-dimensional (2D) materials for realizing next-generation electronics and optoelectronics with attractive physical properties. However, monolayer TMDCs (TMDCs) have various serious issues, such as instability under ambient conditions and low optical quantum yield from their extremely thin thickness of ∼0.7 nm. To overcome these issues, we constructed a hybrid structure (HS) by growing zinc oxide nanorods (ZnO NRs) on a monolayer tungsten diselenide (WSe) using the hydrothermal method. Consequently, we confirmed not only enhanced photoluminescence of WSe but also improved optoelectronic properties by fabricating the HS phototransistor. Through various investigations, we found that these phenomena were due to the antenna and p-type doping effects attributed to the ZnO NRs. In addition, we verified that the optoelectronic properties of TMDCs are maintained for 2 weeks in ambient condition through the sustainable encapsulation effect induced by our HS. This encapsulation method with inorganic materials is expected to be applied to improve the stability and performance of various emerging 2D material-based devices.