Semiconducting tin selenide thin films prepared by heating Se–Sn layers

Deposition of Se thin films of 80–350 nm in thickness from a chemical bath at a deposition yield of more than 95% is reported. These films are utilized to prepare SnSe and SnSe 2 thin films either by heating a vacuum deposited Sn thin film in close contact with the Se thin film at 200 °C in a nitrogen atmosphere for 1 h or by heating a Se–Sn stack in air at 400 °C for about 5 min. By controlling individual film thicknesses and the conditions of heating, SnSe 2 or composite films of SnSe 2 and SnSe are formed. An optical band gap of 1–1.27 eV, electrical conductivity of 0.01–0.2 Ω −1 cm −1 and the photoconductivity of these materials fulfil the basic requirements for their integration into photovoltaic structures.