Engineering the crystallinity of tin disulfide deposited at low temperatures

Abstract

Tin disulfide (SnS₂), which exhibits a two-dimensional (2D) layered structure, is considered to be a promising channel material for thin film transistors because of its high electrical performance and low temperature processibility. In this work, we deposited crystalline SnS₂ at 150 °C using atomic layer deposition (ALD) which is compatible with current electronic device processing methods. And then, crystalline SnS₂ films were annealed to investigate the change in crystallinity. We carried out sulfur annealing of the SnS₂ films at temperatures of 250, 300 and 350 °C. The effects of sulfur annealing were investigated in a mixed gas atmosphere of 100 sccm argon (Ar) and 5 sccm hydrogen (H₂). SnS₂ samples were examined using XRD, TEM, XPS, UV-vis and PL. The crystallinity of the SnS₂ films after annealing was improved, and its grain size became larger compared with the as-deposited SnS₂ film. We also observed a clear two dimensional layered structure of SnS₂ using high resolution TEM. The change in the optical properties of the SnS₂ films was observed using UV-vis and PL.