Thin film Iron Pyrite synthesized by sulfurization of Iron Oxide for application in photovoltaics

Abstract

Iron Pyrite (FeS2) is considered as a promising candidate for photovoltaic application because of its suitable band-gap, very high light absorption coefficient and the abundance of the component elements in the earth's crust. The problem however is that Iron Sulfide has several coexisting phases. Even with the same stoichiometry, it may have two different phases such as pyrite and marcasite. In this report, a phase pure iron pyrite is fabricated on a plain glass and molybdenum coated glass in an atmospheric pressure chemical vapor deposition system (APCVD) by annealing sputtered iron oxide (Fe2O3) in sulfur environment (elemental sulfur) at temperatures higher than 350°C. X-ray Diffraction measurement showed only pyrite phase and energy dispersive spectroscopy (EDS) showed 1:2 ratio for iron to sulfur. Depth profile using X-ray Photoelectron Spectroscopy showed a full conversion of iron oxide into pyrite. Increasing the temperature beyond 350°C, grain size got bigger, but pyrrhotite phase with very low resistivity started to appear.