Vastly enhanced photoresponsivities of phase-controlled tin sulfide thin films

Herein, we reveal extraordinary enhancements in the photoresponsivities of tin sulfide (Sn_xS_y) grown on SiO₂/Si wafers through post-phase transformations induced by electron beam irradiation (EBI) and crystallization. Amorphous Sn_xS_y thin films were formed by room-temperature sputtering, and as-deposited films were subsequently transformed into hexagonal SnS₂ and orthorhombic SnS phases by EBI at 600 and 800 V respectively, for only one minute. The use of a low-energy electron beam was sufficient to fabricate a Sn_xS_y photodetector, with no additional heating required. Less than 10 nm thick Sn_xS_y films with well-defined layer structures and stable surface morphologies were obtained through EBI at 600 and 800 V. The resulting phase-controlled SnS thin-film photodetector prepared using 800 V-EBI exhibited a 40 000-fold increase in photoresponsivity; when illuminated by a 450 nm light source, the active SnS-layer-containing photodetector demonstrated a photoresponsivity of 33.2 mA W^-1.