Air-Stable Violet Phosphorus/MoS 2 van der Waals Heterostructure for High-Responsivity and Gate-Tunable Photodetection.

Violet phosphorus (VP), a newly emerging elemental 2D semiconductor, with attractive properties such as tunable bandgap, high carrier mobility, and unusual structural anisotropy, offers significant opportunities for designing high-performance electronic and optoelectronic devices. However, the study on fundamental property and device application of 2D VP is seriously hindered by its inherent instability in ambient air. Here, a VP/MoS 2 van der Waals heterostructure is constructed by vertically staking few-layer VP and MoS 2 , aiming to utilize the synergistic effect of the two materials to achieve a high-performance 2D photodetector. The strong optical absorption of VP combining with the type-II band alignment of VP/MoS 2 heterostructure make VP play a prominent photogating effect. As a result, the VP/MoS 2 heterostructure photodetector achieves an excellent photoresponse performances with ultrahigh responsivity of 3.82 × 10 5  A W -1 , high specific detectivity of 9.17 × 10 13 Jones, large external quantum efficiency of 8.91 × 10 7 %, and gate tunability, which are much superior to that of individual MoS 2 device or VP device. Moreover, the VP/MoS 2 heterostructure photodetector indicates superior air stability due to the effective protection of VP by MoS 2 encapsulation. This work sheds light on the future study of the fundamental property and optoelectronic device application of VP.