Growth of FeS2 (pyrite) thin films on single crystalline substrates by low pressure metalorganic chemical vapour deposition

Abstract

Thin films of pyrite have been prepared by low pressure metalorganic chemical vapour deposition (LP-MOCVD) from iron pentacarbonyl (Fe(CO)5) and di-tert.-butyl disulphide (TBDS) on Si, GaP and ZnS substrates. It was found that stoichiometric pyrite films without marcasite inclusions could be prepared at deposition temperatures from 450 to 500°C. The films were always polycrystalline but showed a preferred orientation in the (111) direction at high temperatures (475°C). The grain sizes in the range 1–10 μm depend on the substrate orientation, the growth rate and the substrate temperature. The layer composition is stoichiometric (FeS2) up to 500°C. The formation of pyrrhotite phases (Fe1−xS) occurs at higher temperatures, when the sulphur partial pressure in the gas phase is too low to compete against the decomposition pressure of sulphur in the pyrite layer.