INVESTIGATIONS ON POLYCRYSTALLINE CUGATE2 THIN-FILMS

Polycrystalline and single-phase CuGaTe2 thin films (0.4-1.0 mu m thic kness) were prepared by flash evaporation of the pre-reacted material, synthesized from its constituent elements. The films were deposited o n glass substrates at temperatures in the range 303-623 K. The physica l behaviour of the films was found to be highly influenced by the subs trate temperature, T-s. The films formed at T-s = 523-573 K were nearl y stoichiometric and exhibited (112) preferred orientation with tetrag onal structure. The evaluated lattice parameters were a = 6.025 Angstr om and c = 11.996 Angstrom. The electrical conductivity of the films v aried in the range 10-10(2) Ohm cm. Two activation energies correspond ing to shallow and deep acceptor levels were observed. The films showe d a three-fold optical structure with the bandgaps at 1.23 eV, 1.28 eV and 1.98 eV. The optical constants, dielectric constant, plasma frequ ency and the effective mass of the charge carriers were computed. The results are discussed to study the suitability of CuGaTe, films for so lar cell application.