A MoS2/Au NPs/WS2 heterostructures photodetector with high on/off ratio and low standby power consumption

Two-dimensional transition metal dichalcogenides (TMDCs) hold great promise for optoelectronic devices owing to their unique electronic and optical properties. However, their typically high dark current severely compromises the photodetection performance. To overcome this challenge, we fabricated a type-II band-aligned MoS 2 /WS 2 heterostructures and innovatively incorporated a layer of gold nanoparticles (Au NPs) at its interface. The resulting MoS 2 /Au NPs/WS 2 heterostructures exhibits drastically suppressed dark current while well preserving the photocurrent. Scanning Kelvin probe force microscopy (SKPFM) measurements confirm the type-II band alignment. We demonstrate that in the dark, the Au NPs in contact with MoS 2 create an electron-depletion region in the conduction band, effectively blocking the majority carrier transport and thus reducing the dark current. Under illumination, however, the photo-generated electrons possess sufficient energy to overcome this barrier, leaving the photocurrent largely unaffected. Therefore, under a 5 V bias, compared with the pristine MoS 2 /WS 2 heterostructures, the MoS 2 /Au NPs/WS 2 heterostructures device exhibits a reduction in dark current density by approximately 2.27 × 10 3 times, while the photocurrent density shows only a slight decrease of about 2.19 times. This remarkable contrast leads to a significant enhancement of the light-to-dark current ratio from 4.71 × 10 1 to 5.01 × 10 4 and an expansion of the linear dynamic range from 46.81 dB to 107.58 dB. Furthermore, the suppressed dark current directly translates to a ∼2.27 × 10 3 -fold reduction in standby power consumption under dark conditions. Our work, integrating plasmonic nanoparticles into the interface of a TMDCs heterostructures, provides a novel and effective strategy for engineering high-performance, low-power two-dimensional photodetectors.