Effect of Mo Vacancy on the Photoresponse of Bilayer MoS2 Film

Photodetectors that can detect light over a broad spectral range have attracted significant attention. Recently, molybdenum disulfide (MoS2), a known transition metal dichalcogenide, is considered a good photodetector material. In this study, MoS2 film was prepared by metal-organic chemical vapor deposition (MOCVD) on an SiO2/Si substrate. The effect of Mo vacancies on the structural, electrical, and optical properties of MoS2 films was analyzed. Results show that the synthesized MoS2-based phototransistor exhibits a photoresponsivity as high as 125 A/W at 0.02 mW power density of the 850 nm laser at room temperature (300 K). The Mo vacancies were confirmed in the MoS2 bilayer through XPS measurements. MOCVD-grown bilayer MoS2-based phototransistors with Mo vacancies allowed the detection of a wider wavelength range of 400-1150 nm. Thus, introducing Mo vacancies improved the optoelectronic properties of MoS2 phototransistors.