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  Kaigawa, R.; Ban, K.; Merdes, S.; Dittrich, T.; Klenk, R.: In and Ga diffusion of Cu(In, Ga)Se₂ and Cu(In, Ga)S₂ films instantaneously prepared in a non-vacuum process. Energy Procedia 10 (2011), p. 297-302

10.1016/j.egypro.2011.10.194

Abstract:
When Cu(In,Ga)(S,Se)2 is prepared by heating metal precursor films in chalcogen atmosphere (sequential process) the resulting films typically show a gradient in the Ga/(In+Ga) ratio over the depth of the film. This is generally observed for reaction periods ranging from a few minutes (rapid thermal processing) to several hours. In this work we have investigated the Ga distribution in films where the reaction period was reduced to one second. As previously reported, such instantaneous synthesis can be achieved by spraying elemental Cu, In, S, Se particles onto a Mo foil, and then using a spot welding machine to pass very high currents through the Mo foil. In this work, the metal precursors were evaporated onto the Mo foil, and chalcogen particles were sprayed ontop. The Ga distribution is derived from secondary ion mass spectroscopy (SIMS) and x-ray diffraction (XRD). We report on the influence of parameters such as the electrical power applied, the presence of Cu-excess, and the type of chalcogen (selenium or sulphur).