Transformation of amorphous iron oxide thin films predeposited by spray pyrolysis into a single FeSe2-phase by selenisation

The present paper investigates a simple and non-toxic method to transform amorphous iron oxide pre-deposited by spray pyrolysis of FeCl3·6H2O (0.03 M)-based aqueous solution onto glass substrates heated at 350 °C into FeSe2 thin films. The amorphous iron oxide films were heat treated under a selenium atmosphere (10−4 Pa) at different temperatures for 6 h. X-ray diffraction (XRD) was used to investigate the structure of the obtained films. Single FeSe2-phase films having good crystallinity were obtained at a selenisation temperature of 550 °C. Optical analyses of the FeSe2 films obtained at 550 °C enabled us to deduce a large absorption coefficient (α>105cm-1, λ<800nm). Surface scanning electron microscopy (SEM) observations show inhomogeneous films. Electrical conductivity of the as-prepared films was measured at high and low temperatures.