ESR and NMR studies of CuInSe 2 crystals having controlled component activities

Abstract

CIS (CuInSe 2) crystals from several sources were investigated by Electron Spin Resonance (ESR) and Nuclear Magnetic Resonance (NMR). The crystals were annealed with various Se or Cu thermodynamic activities so as to give well defined ternaries from the chemical point of view. Several paramagnetic centers were found and studied. They could be attributed either to residual impurities, surface or bulk intrinsic defects. The ESR spectra obtained for different temperatures and microwave power levels yielded the fundamental characteristics of the paramagnetic centers. The study of the dipolar broadening of the ESR lines associated with intrinsic defects showed that the defect distribution is inhomogeneous and that intrinsic defects tend to form aggregates. 115In and 63Cu NMR signals are also discussed. The origin and behavior of intrinsic defects in CIS are discussed in light of these new ESR and NMR data. The results are also compared to those previously reported on coevaporated CIGS (Cu(In, Ga)Se 2) thin film powders.