Preparation and characterization of Cu_2ZnSnSe_4 thin films grown from ZnSe and Cu_2SnS_3 precursors in a two stage process

摘要

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 Cu_2ZnSnSe_4 (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 Cu_2ZnSnSe_4 compound, grown with tetragonal K?sterite 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