Large Single Crystal SnS2 Flakes Synthesized from Coevaporation of Sn and S

Remarkable properties of layered metal dichalcogenides and their potential applications in various fields have raised intense interest worldwide. We report tens of microns-sized ultrathin single crystal SnS2 flakes grown on amorphous substrates using a simple one-step thermal coevaporation process. X-ray pole figure analysis reveals that a majority of flakes are oriented with the (0001) plane parallel to the substrate and a preferred fiber texture. For few-layer-thick SnS2, Moire patterns of 6-fold and 12-fold symmetries are observed by transmission electron microscopy imaging and diffraction. These patterns result from the relative rotation between SnS2 layers in the ultrathin flake. The 12-fold symmetry is consistent with a known quasicrystal pattern. The photoluminescence spectrum supports that these ultrathin flakes possess a direct bandgap. Carrier lifetime measured by time-resolved photoluminescence of a single flake is a few nanoseconds. These results improve our understanding of the formation and shape of ultrathin SnS2 flakes.