Enhancing and Broadening the Photoresponse of Monolayer MoS Based on Au Nanoslit Array.

Two-dimensional molybdenum disulfide (MoS), featuring unique optoelectronic properties, has attracted tremendous interest in developing novel photodetection devices. However, the limited light absorption and small carrier transport rate of the monolayer MoS result in low photoresponse, and the large band gap limits its detection range in the visible region. In this study, we propose a nanoslit array-MoS hybrid device architecture with enhanced and broadened photoresponse. The nanoslit array can localize free-space light to achieve strong interactions with MoS, and acts as the channel to improve charge transport. As a result, the Au nanoslit array-MoS hybrid detector exhibits a nearly 100-fold increase in photocurrent compared to the pure MoS device. More importantly, the hybrid device can broaden the photoresponse to the optical communication band of 1550 nm which is lower than the band gap of MoS, by efficiently utilizing the hot carriers generated by the Au nanoslits. The experimental results are supported by both theoretical analysis and numerical simulation. Since our demonstration leverages the engineering of the hybrid photodetectors with metal nanostructures rather than semiconductor materials, it should be universal and applicable to other devices for broadband, high-efficiency photoelectric conversion.