Wavelength-selectivity polarization dependence of optical absorption and photoresponse in SnS nanosheets

The optical and optoelectronic characteristics of SnS nanosheets with strong anisotropic crystal structure are researched. Transmission electron microscopy and polarized Raman spectra are used to determine the crystal orientation of SnS nanosheets. The photodetector based on SnS nanosheets exhibits the carrier mobility of 37.75 cm²/V·s_, photoresponsivity of 310.5 A/W and external quantum efficiency of 8.56 × 10⁴ % at 450 nm. Optical absorption around the absorption edge presents obvious polarization sensitivity with the highest optical absorption dichroic ratio of 3.06 at 862 nm. Due to anisotropic optical absorption, the polarized photocurrent appears as the periodic change affected by the polarized direction of the incident light at 808 nm. Overall, SnS nanosheets show good potential in the future application of the polarized photodetectors for specific wavelength.