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.

Strain engineering provides an important strategy to modulate the optical and electrical properties of semiconductors for improving devices performance with mechanical force or thermal expansion difference. Here, we present the investigation of the local strain distribution over few-layer MoS₂ bubbles, by using scanning photoluminescence and Raman spectroscopies. We observe the obvious direct bandgap emissions with strain in the few-layer MoS₂ bubble and the strain-induced continuous energy shifts of both resonant excitons and vibrational modes from the edge of the MoS₂ bubble to the center (10 μm scale), associated with the oscillations resulted from the optical interference-induced temperature distribution. To understand these results, we perform ab initio simulations to calculate the electronic and vibrational properties of few-layer MoS₂ with biaxial tensile strain, based on density functional theory, finding good agreement with the experimental results. Our study suggests that local strain offers a convenient way to continuously tune the physical properties of a few-layer transition metal dichalcogenides (TMDs) semiconductor, and opens up new possibilities for band engineering within the 2D plane.