Optical and electrical properties of SnSe2 and SnSe thin films prepared by spray pyrolysis

Tin diselenide thin films were prepared by spray pyrolysis technique using SnCl2·H2O and 1,1-dimethyl-2-selenourea as precursor compounds with a Se:Sn atomic ratio of 1:1 in the starting solution. The deposition process was carried out in the substrate temperature range of 275 °C to 400 °C using two solution flow rates of 5 ml/min and 8 ml/min. The phases of SnSe2 were obtained when the deposition was carried ou at a flow rate of 5 ml/min, while for the films deposited at 8 ml/min mixed phases of SnSe2/SnSe were observed. Heat treatment of the deposited SnSe2/SnSe thin films in an atmosphere of 95% N2 and 5% H2 led to crystallization of the SnSe compound. The as deposited SnSe2 thin films have an optical band gap of 1.59 eV with n-type electrical conductivity in the range of 10− 1 (Ω cm)− 1 to 101 (Ω cm)− 1. The annealed thin films have an optical band gap of 0.81 eV and show p-type electrical conductivity of 2 × 10− 1 (Ω cm)− 1.