Iron pyrite (FeS2) is a promising earthabundant semiconductor for thin film solar cells because of its exceptional optical absorption coefficient and suitable band gap. However, recent studies suggest surface defects, impurities, and mixed phases of FeS2 may cause a photovoltage reduction. Utilizing tunable-energy synchrotron x-ray photoemission, absorption, and valence photoemission spectroscopies, we explore the surface and electronic structures of pyrite thin films grown by metal organic chemical vapor deposition (MOCVD). We also resolve different types of sulfur chemical states and elemental composition depth profiles on the surface of substrate-dependent pyrite thin films. Additionally, we study the in situ oxidation process under different oxidizing environments by Ambient Pressure Photoemission Spectroscopy. Our results suggest that the surface monosulfide species is oxidized first, and the reduction in the total density of states near the Fermi surface is caused by oxide layers.

Surface structure and depth profile study of pyrite thin films grown by MOCVD

243rd National Meeting (2012)

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