Physico-chemical characterisation of Cu(In,Al)Se2 thin film for solar cells obtained by a selenisation process

Cu(In,Al)Se2 thin films are investigated for their application as absorber layer material for solar cells. Films are elaborated by selenisation of multilayer metallic precursors deposited by thermal evaporation. In order to minimize the oxidation of the aluminium during the precursor deposition, an alternative deposition method using a Cu–Al eutectic is used. Films are characterized by X-ray diffraction, electron probe microanalysis, scanning electron microscopy, and optical measurements. These measurements show that most of the films are crystallized in the chalcopyrite structure and have the expected optical properties and composition. In some cases, the aluminium segregates and the films behave like CuInSe2. In all cases, the films are not oxidized (less than 1 at.% of O2).