Cu₂Si_xSn_1-xS₃ thin films prepared by reactive magnetron sputtering for low-cost thin film solar cells

We report the preparation of Cu₂Si_xSn _1-xS₃ thin films for thin film solar cell absorbers using the reactive magnetron co-sputtering technique. Energy dispersive spectrometer and x-ray diffraction analyses indicate that Cu₂Si _1-xSn_xS₃ thin films can be synthesized successfully by partly substituting Si atoms for Sn atoms in the Cu ₂SnS₃ lattice, leading to a shrinkage of the lattice, and, accordingly, by 2θ shifting to larger values. The blue shift of the Raman peak further confirms the formation of Cu₂Si_xSn _1-xS₃. Environmental scanning electron microscope analyses reveal a polycrystalline and homogeneous morphology with a grain size of about 200-300 nm. Optical measurements indicate an optical absorption coefficient of higher than 10⁴ cm^-1 and an optical bandgap of 1.170.01 eV.