Artificial control of in-plane anisotropic photoelectricity in monolayer MoS2

Intrinsic linear polarized optics discovered in anisotropic two-dimensional (2D) materials has attracted intense interest for polarization-sensitive optical and optoelectronic applications, such as black phosphorous, ReSe2, etc. However, the lack of matured method to synthesize high-quality, large-scale and air-stable 2D materials with anisotropic properties, is still an obstacle for practical applications. Monolayer molybdenum disulfide (MoS2), which exhibits strong direct-band-gap light-harvesting properties, can be grown maturely. But unfortunately, MoS2 does not show linear dichroism owing to its in-plane isotropic crystalline symmetry. We, herein, for the first time, report on an artificial control of extrinsic linear polarized photoelectric effect in monolayer MoS2, by successfully controlling its anisotropic degree of in-plane crystal symmetry via artificially induced uniaxial tensile strain. Strong linear polarization-sensitive photodetection from visible to near-infrared range is realized for monolayer MoS2-based device, and the polarization anisotropic ratio can reach up over 2.0 under 4.5% strain. The observation is supported by combination of experiment-theory study on polarized Raman spectrum and optical absorption under gradually applied strains. Our results have demonstrated that the artificial-controlled symmetry reducing of MoS2 is a promising strategy to achieve high performance polarization photodetection. This method can also be extended to other 2D materials, which potentially opens up a new field to endow isotropic 2D materials with anisotropic functionalities by artificial structure engineering.