Electrically Modulated Wavelength-Selective Photodetection Enabled by MoS2/ZnO Heterostructure

Abstract

Regardless of the significant progress in photodetectors (PDs), most conventional technologies are equipped with optical filters for spectral discrimination, which results in expensive circuitry as well as a high incidence of energy loss. Different from traditional PDs, a ${\mathrm{Mo}\mathrm{S}}_{2}/\mathrm{Zn}\mathrm{O}$ heterostructure-based PD is demonstrated that exhibits a bias-dependent switchable spectral response. A low-band-gap ${\mathrm{Mo}\mathrm{S}}_{2}$ thin film is vertically stacked on top of a high-band-gap $\mathrm{Zn}\mathrm{O}$ film that allows selective charge transport from each layer by modulating the applied bias, resulting in a fine discrimination between visible and near-infrared (NIR) light. Under a lower applied bias, a dominant photoresponse in the visible region by the $\mathrm{Zn}\mathrm{O}$ film is observed, whereas an enhanced response in the NIR region is obtained at higher bias, which is attributed to the generation of charge carriers in the ${\mathrm{Mo}\mathrm{S}}_{2}$ region. The excellent figures of merit obtained in the study attest to the high quality of the device, paving the way for fabricating energy-efficient imaging systems free of optical filters.