Tin disulfide-an emerging layered metal dichalcogenide semiconductor: Materials properties and device characteristics

Layered metal dichalcogenides have attracted significant interest as a family of single- and few-layer materials that show new physics and are of interest for device applications. Here, we report a comprehensive characterization of the properties of tin disulfide (SnS₂), an emerging semiconducting metal dichalcogenide, down to the monolayer limit. Using flakes exfoliated from layered bulk crystals, we establish the characteristics of single- and few-layer SnS₂ in optical and atomic force microscopy, Raman spectroscopy and transmission electron microscopy. Band structure measurements in conjunction with ab initio calculations and photoluminescence spectroscopy show that SnS₂ is an indirect bandgap semiconductor over the entire thickness range from bulk to single-layer. Field effect transport in SnS₂ supported by SiO₂/Si suggests predominant scattering by centers at the support interface. Ultrathin transistors show on-off current ratios >10⁶, as well as carrier mobilities up to 230 cm²/(V s), minimal hysteresis, and near-ideal subthreshold swing for devices screened by a high-k (deionized water) top gate. SnS₂ transistors are efficient photodetectors but, similar to other metal dichalcogenides, show a relatively slow response to pulsed irradiation, likely due to adsorbate-induced long-lived extrinsic trap states.