PERTURBED ANGULAR-CORRELATIONS STUDY OF THIN CU-IN FILMS

Perturbed angular correlations (PAC) of gamma rays using In-111 nuclear probes are applied to study the phase formation in thin Cu-In films used as precursors for the preparation of CuInS2 by reactive annealing in H2S atmosphere. The Cu-In films are prepared by the successive thermal evaporation of In and Cu in UHV. By means of PAC we are able to obtain a true image of all In-containing phases in the sample. Improved PAC parameters for the phases Cu7In3, Cu11In9, and CuIn2 are given, and the stability of the phase CuIn2 is determined. The phase compositions of copper-rich, stoichiometric, and indium-rich precursors are investigated after annealing procedures between room temperature and 150 degrees C. The phase formation in this temperature region is governed by two fast diffusion processes which lead to the appearance of Cu11In9 and CuIn2, respectively, as the only intermetallic compounds. (C) 1995 American Institute of Physics.