Preparation and characterization of Cu₂ZnSnSe₄ thin films grown from ZnSe and Cu₂SnS₃ precursors in a two stage process

Compound of the kesterite familie has been considered as an alternative absorber layer in the manufacture of thin film solar cells due to its earth abundant and environmental friendly constituents and high absorption coefficient. In this work we propose a new route to grow single phase Cu₂ZnSnSe₄ (CZTSe) thin films with tetragonal-kesterite type structure; this consist in sequential evaporation of thin films of CuSe, SnSe and ZnSe in a two stage process. Measurements of X-ray diffraction (XRD) revealed the formation of the Cu₂ZnSnSe₄ compound, grown with tetragonal Kësterite type structure. Optical characterization performed through spectral transmittance measurements established that this compound has high absorption (absorption coefficient > 10⁴ cm-1) and a forbidden energy gap of 1.46 eV; these results indicate that the CZTSe thin films we have prepared has properties suitable for later use as absorber layer in solar cells. Results regarding electrical transport properties determined from temperature dependent conductivity measurements are also reported.