Comparison of material properties of CuInSe2 films produced by reaction of metallic alloys to H2Se/Ar and elemental Se vapour

In this study, CuInSe2 thin films were produced by the reaction of identical precursors to elemental Se vapour and H2Se/Ar gas. In order to compare the respective growth processes, the reaction temperature was varied between 300degreesC and 600degreesC, while all other parameters were kept constant. For a given set of experimental parameters, significant differences were observed in terms of crystalline quality and in-depth compositional uniformity. At low selenization temperatures below 400 C, the reaction process was incomplete, irrespective of the selenization process considered. Reaction of precursors to H2Se/Ar at temperatures above 400degreesC (for 40 min), produced fully reacted films with uniform and dense surface morphologies and a high degree of in-depth compositional uniformity. Under similar conditions, Se vapour treated samples had nonuniform surface morphologies with an associated relatively large variation in the Cu/In atomic ratio and Se concentration through the depth of the samples. This comparative study identifies the important differences between the two reactive processes and the advantages in using H2Se/Ar as a chalcogenide source.