Structural studies on SnS films grown by a two-stage process

Abstract

Thin films of SnS have been grown by a novel two-stage process. It involves sulphurisation of thin metallic tin precursor layers in a vacuum furnace using a graphite box. The precursor layers were annealed at different temperatures in the range of 100–400 °C in excess ambient sulphur. The layers, annealed at temperatures 300–350 °C, were polycrystalline with a strong {111} preferred orientation. These layers had orthorhombic crystal structure with a grain size of 100 nm and exhibited stoichiometric composition. The precursor layers, reactively annealed at temperatures lower than 300 °C, had secondary phases such as SnS 2 and Sn 2S 3 with a grain size of 50 nm. However, the Sn layers, annealed at higher temperature >350 °C, had an additional phase of SnS 2 along with the SnS phase and showed deviation from stoichiometry with a deficiency of sulphur. The results were analysed systematically to develop the growth process.