Synthesis of Pyrite (FeS2) Thin Films by Low-Pressure MOCVD

Abstract

Thin films of iron disulfide have been prepared by low-pressure CVD (LPCVD) from iron(III) acetylacetonate (Fe(acac) 3 ), tert-butyldisulfide (TBDS), and hydrogen. The influence of the relevant CVD parameters on the growth rate, chemical composition (stoichiometry), morphology, crystalline phases, and contaminants has been examined. Pyrite thin films with a uniformity variation of less than 5 % over a length of 10 cm are obtained in a hot-wall LPCVD reactor. The present study shows that these films are deposited without detectable iron sulfide (FeS) phases at temperatures from 300 °C up to 340 °C on glass and silicon substrates. Growth rates vary between 0.2 nm min -1 and 12 nm min -1 . In all cases, the films are polycrystalline pyrite with an indirect bandgap of 0.95 ± 0.05 eV, and a dark specific resistance of 0.5-1.0 Ω cm. The absorption coefficient of the films is 3 ± 1 × 10 5 cm -1 at λ = 500 nm.