Evolution of CuInSe2 (1 1 2) surface due to annealing: XPS study

Abstract The evolution of the elemental composition and chemical bonding of the (1 1 2) surface of CuInSe 2 single crystals, cleaned by 4 keV N + and then annealed at temperatures from 200 to 750 °C in vacuum, was analysed using X-ray photoelectron spectroscopy. After annealing at temperatures over 500 °C but below 700 °C the elemental composition approached to CuIn 3 Se 5 . Following annealing at 650 °C the surface structure was examined using X-ray photoelectron diffraction. Experimental 2π-projection maps were constructed from the full hemispherical intensity distributions of In, Cu photo- and Se Auger-electron emission. These maps, the elemental composition, chemical bonding and the Cu 2 Se–In 2 Se 3 phase diagram suggested the following three options for the surface compound (each with a sphalerite-based structure): (1) the single-phase state CuIn 3 Se 5 , (2) a mixture of In 2 Se 3 and CuInSe 2 , (3) a mixture of In 2 Se 3 and Cu 2 Se.