Gap-surface-plasmon induced polarization photoresponse for MoS2-based photodetector

Polarization-sensitive photodetectors based on two-dimensional (2D) materials have shown more attractive application prospects compared to traditional thin-film photodetectors due to their atomic thickness, tunable bandgap, high mobility and strong light–matter interactions. Among them, 2D molybdenum disulfide (MoS2) has drawn numerous attentions in photodetection due to its wide spectral range, remarkable photoresponsivity and fast photo-switching rate. However, the isotropic crystal structure of MoS2 hampers its application in the polarization-sensitive detection, which is highly desired in military and civilian applications. In this paper, we demonstrated an integration of plasmonic nanocavity with monolayer MoS2 to achieve high photoresponsivity and polarization-sensitive photodetector. With the significant enhancement of electromagnetic field provided by the gap-surface-plasmon (GSP), we achieved a significant photoluminescence (PL) enhancement of 24-fold. Relying on the enhanced light absorption by our plasmonic nanocavity, which generally facilitates photo-generation of electron–hole pairs in MoS2, we achieved a high photoresponsivity of 1.88 A/W and degree of linear polarization (DOLP) of 0.8 at the excitation wavelength of 633 nm. Our work provides a feasible and universal solution to realize polarization-sensitive photodetector of MoS2 for high-performance and polarization-sensitive photodetectors. [graphic not available: see fulltext]