Electron spin resonance studies of Cu(In,Ga)Se2 thin films

Cu(In,Ga)Se-2 (CIGS) powders obtained from co-evaporated films were investigated by electron spin resonance (ESR). They were compared to CuInSe2 and CIGS powder annealed under various Se pressures. Several paramagnetic centers were found and studied. One of the signals was identified as originating from Fe (III) ions and their concentration in co-evaporated, device grade quality CIGS (10(17) cm(-3)) was obtained. Other signals were attributed either to surface or bulk intrinsic defects. The ESR spectra obtained for different temperatures and microwave powers yielded the fundamental characteristics of the paramagnetic centers. The study of the dipolar broadening of the ESR lines of the intrinsic defects showed that the defect distribution is inhomogeneous and that they tend to form aggregates. The origin and behavior of intrinsic defects in CIGS will be discussed in light of these new ESR data. (C) 2003 Elsevier Science B.V. All rights reserved.