Giant-Enhanced SnS2 Photodetectors with Broadband Response through Oxygen Plasma Treatment

Layered tin disulfide (SnS2) is a vital semiconductor with versatile functionality due to its high carrier mobility and excellent photoresponsivity. However, the intrinsic defects V-s (sulfur vacancies), which cause Fermi level pinning (significant metal contact resistance), hinder its electrical and optoelectrical performance. Herein, oxygen plasma treatment is employed to enhance the optoelectronic performance of SnS2 flakes, which results in artificial sub-bandgap in SnS2. Consequently, the broadband photosensing (300-750 nm) is remarkably improved. Specifically, under 350 nm illumination, the O-2-plasma-treated SnS2 photodetector exhibits an enhanced photoresponsivity from 385 to 860 A W-1, the external quantum efficiency and the detectivity improve by one order of magnitude as well as increase the photoswitching response improvement by two orders of magnitude for both rising (tau(r)) and decay (tau(d)) time. This artificial sub-bandgap can both improve the photoresponse and broaden the response spectra, which paves a new path for the applications of optoelectronics.