Control of V-Se- defect levels in CuInSe2 prepared by rapid thermal processing of metallic alloys

The reaction of metallic alloys to H2Se/Ar is a promising technique to prod uce device quality CuInSe2 thin films. However, up to now the controllabili ty of the film quality has been critically influenced by the segregation of secondary phases during growth. We indicate in this study that this phenom enon is strongly related to the selenization reaction temperature, and espe cially to the ramping procedure followed to the final selenization temperat ure. Metallic precursors which were slowly heated to temperatures around 40 0 degrees C are characterized by inhomogeneous film morphologies and X-ray fluorescence (XRF) measurements revealed a strong segregation of In towards the Mo back contact. In contrast, rapid heating of samples in H2Se/Ar to t emperatures above 400 degrees C resulted in uniform and dense films with a high degree of compositional uniformity through the thickness of the sample s. Transmission electron microscopy (TEM) indicated the presence of a low d ensity of planar defects in these optimized films. Low temperature photolum inescence (PL) studies demonstrated that the optical properties of these po lycrystalline thin Alms are very sensitive to post-growth treatment in Ar/H -2 and O-2. (C) 2000 published by Elsevier Science S.A. All rights reserved .