Preparation of Ordered Vacancy Chalcopyrite-Type CuIn3Se5 Thin Films

Abstract
Polycrystalline CuIn3Se5 films were successfully prepared by three-source coevaporation with controlling and shielding of the molecular beams from elemental sources. The CuIn3Se5 film exhibited good chemical homogeneity and an ordered vacancy chalcopyrite-type structure with lattice constants of a=5.742 Å and c=11.486 Å. High-resolution transmission electron microscopy showed that the CuIn3Se5 film had a columnar microstructure and each grain contained a high density of twins in {112} planes. The band-gap energy of the film was determined to be 1.23 eV from optical transmission measurements. The film showed n-type conduction and low conductivity of 3.7×10-7/ Ω·cm. These characteristics of the CuIn3Se5 film are compared with those of the chalcopyrite-type CuInSe2 film.