Abstract
Amorphous iron oxide films were prepared by spray pyrolysis of FeCl
3·6H
2O (0.03 M)-based aqueous solution onto glass substrates heated at 350 °C. Rust red iron oxide films were obtained. Crystallized iron oxide films were achieved after heat treatments in vacuum. X-ray diffraction (XRD) patterns show two polycrystalline iron oxide phases. The dominant phase corresponds to Fe
2O
3 and the minor one corresponds to traces of FeOOH, which transforms immediately to Fe
2O
3 after further heat treatment. Scanning electron microscopy (SEM) microanalyses show that stoichiometric Fe
2O
3 films were obtained. Sulphuration at 450°C for 6 h under vacuum (10
−4 Torr) transforms the amorphous iron oxide films into FeS
2-pyrite films having good crystallinity. SEM images show that the FeS
2 films are granular. The homogeneity and both dimension and distribution of the FeS
2 grain sizes were found to depend on the sulphuration temperature of the pre-deposited amorphous iron oxide films. First optical analyses enabled us to deduce a direct energy band gap of about 0.72 eV. All the prepared FeS
2 films show p-type conduction.