Material properties of CuInSe2 prepared by H2Se treatment of CuIn alloys

CuInSe2 thin films were prepared by the selenization of metallic precursors in an atmosphere containing H2Se gas. Device-quality (homogeneous and dense films with excellent compositional uniformity) CuInSe2 films were obtained when Cu/In/Cu structures were exposed to H2Se/Ar while the temperature was ramped between 150 and 400 degrees C. Auger studies indicated that the composition of the films was relatively uniform through their thickness. Transmission electron microscopy studies indicated that copper-rich samples exhibited large facetted grains (1-4 mu m) with relatively low defect density, Indium-rich fil ms were characterized by relatively small grains (0.2-0.8 mu m), which were highly defected. CuInSe2/CdS/ZnO solar cells were fabricated using chemically etched (in KCN) copper-rich CuInSe2 absorber films, and conversion efficiencies of 5% were obtained without the use of an antireflection coating. (C) 1998 Kluwer Academic Publishers.