Synthesis and characterization of nanocrystalline SnS films grown by thermal evaporation technique

The SnS films were grown on glass substrates using the thermal evaporation technique at different substrate temperatures (Ts) varied from 20 to 300°C, and their physical properties were studied with appropriate techniques. While increasing Ts, the sulfur content in the films decreased and the Sn to S atomic percent ratio increased from 1.01 to 1.42. The structural studies showed that most of the crystallites in the films were grown along [111] direction and their grain size increased between ∼18 and 41 nm with the increase of Ts. The SnS films grown at Ts =300°C exhibited considerably low electrical resistivity of ∼43 cm with an average grain size of ∼40 nm. These films also exhibited a direct optical bandgap of ∼2.0 eV with a high absorption coefficient, ∼ 106 cm-1. These results indicate that the physical properties of nanocrystalline SnS films are comparable to the properties of bulk as well as microstructured SnS films and are suitable for photovoltaic or nanoquantum-well device applications.