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 center dot 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 degrees C to 400 degrees 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% N-2 and 5% H-2 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) (Omega cm)(-1) to 101 (Omega cm)(-1). The annealed thin films have an optical band gap of 0.81 eV and show p-type electrical conductivity of 2x10(-1) (Omega cm)(-1). (C) 2013 Elsevier B.V. All rights reserved.