Photoresponsivity Enhancement of Monolayer MoS2 by Silicon Quantum Dots

Abstract

Hybrid 2D/0D structures with various 2D materials and 0D quantum dots (QDs) have been studied to overcome the limitations of 2D materials. In this work, a hybrid structure with MoS2 and silicon quantum dots (Si QDs) as a photodetector is developed. The I–V transfer characteristics show a threshold voltage shift after decorating Si QDs on MoS2, which results from an n‐type doping effect to the MoS2 channel from the Si QDs. The field‐effect mobility of the MoS2/Si QDs device is increased by ≈5.8 times compared with that of the bare MoS2 device. It is understood that the mobility enhancement is attributed to the surface defect passivation of MoS2 at the interface with Si QDs. It is observed that the photoresponsivity of the MoS2/Si QDs structure is improved by ≈7.7 times compared with that of the bare MoS2 device under 500 nm illumination. Additionally, it is observed that the photoluminescence (PL) intensity of MoS2 is increased about 4.5 times after decoration of Si QDs. The band alignment as type I at the interface between the Si QDs and MoS2 is interpreted. The mobility enhancement and the photoexcited charge transfer (CT) between the MoS2 and the Si QDs due to the illumination lead to enhancing the photoresponsivity of the MoS2/Si QDs hybrid structure.