Chalcogenide thin films deposited by rfMS technique using a single quaternary target

Highlights: • Cu(In,Ga)Se2 chalcogenide thin films were deposited from a single quaternary target. • SEM images of the samples show homogeneous thin films with uniform thickness. • The samples have a tetragonal structure with the (112) plane parallel to the substrate surface. • The increase of thickness of the chalcogenide determined a decrease of optical bandgap. - Abstract: Thin films of chalcogenide, Cu(In_,Ga)Se₂ have been obtained using a single quaternary target by radio frequency magnetron sputtering method, with thickness in the range 750 nm to 1200 nm. X-ray photoelectron spectroscopy investigations showed, that the composition of Cu(In_,Ga)Se₂ thin films was very similar to that of the used target CuIn_0.75Ga_0.25Se₂. Identification of the chemical composition of Cu(In_,Ga)Se₂ thin films by XPS performed in high vacuum, emphasized that the samples exhibit surface features suitable to be integrated into the structure of solar cells. Atomic Force Microscopy and Scanning Electron Microscopy investigations showed that surface morphology was influenced by the increase in thickness of the Cu(In_,Ga)Se₂ layer. From X-Ray Diffraction investigations it was found that all films were polycrystalline, having a tetragonal lattice with a preferential orientation along the (112) direction. The optical reflectance as a function of wavelength was measured for the studied samples. The increase in thickness of the Cu(In_,Ga)Se₂ absorber determined a decrease of its optical bandgap value from 1.53 eV to 1.44 eV. The results presented in this paper showed an excellent alternative of obtaining Cu(In_,Ga)Se₂ compound thin films from a single target.