Optoelectronic properties of laser-beam-patterned few-layer lateral MoS2 Schottky junctions

Abstract

Atomically thin (or few-layer) two-dimensional transition metal dichalcogenide (TMDC) materials have various unique optoelectronic properties, which bring advantages for application to flexible solar cells and photodetectors, by bandgap engineering via van der Waals hybridization. TMDCs have crystal phase structures, such as the 2H semiconducting phase and the 1T (or 1T′) metallic phase. Recently, we demonstrated the creation of few-atom-layer 1T-metal/2H-semiconductor molybdenum disulphide (MoS2) lateral Schottky junctions by using electron beam (EB) irradiation and revealed their unique optoelectronic properties. However, the 1T phase is metastable, whereas the 1T′ phase is more stable and useful for various applications. Here, we create a few-layer 1T′-metal phase MoS2 by laser beam irradiation, which is a simpler, convenient, and low-cost method compared to EB irradiation. We observe unique optoelectronic features of the few-atom-layer 1T′-metal/2H-semiconductor lateral Schottky junctions in reverse bias voltage regions, such as an effective barrier height of ∼0.15 eV, highly efficient photogeneration ratios (>20%), and high sensitivity to photoirradiation angles without degradation for one month. These properties show great promise for application to highly efficient, flexible, and semitransparent photodetectors and solar cells with long-term reliability.