Local atomic environment of Cu:CdTe thin film alloys

We have used X-ray absorption spectroscopy of the K-edge of each element in a Cd0.85Cu0.15Te thin film to investigate the local atomic structure around each constituent element. X-ray absorption near edge spectra reveal that the local electronic structure around Cd and Te atoms is similar to that of undoped CdTe, while that of Cu is different from that encountered in Cu metal. X-ray absorption fine structure spectra show that while the Cd near neighbor environment is similar to that of undoped CdTe, the Te environment shows differences compared with that found in undoped CdTe, consistent with Cu entering substitutionally for Cd. The Cu nearest neighbor environment suggests the presence of Cu-metal ligands characteristic of Cu metal clusters. These results imply the occurrence of microscopic phase separation in this material in variance with X-ray diffraction results that show a single crystalline phase. (C) 2000 Elsevier Science Ltd. All rights reserved.