Raman spectroscopy of Cu Sn S ternary compound thin films prepared by the low cost spray pyrolysis technique

Cu Sn S CTS thin films were deposited onto bare and molybdenum Mo coated glass substrates by means of the spray pyrolysis technique under different conditions. The CTS thin films obtained are shown, by means of Raman spectroscopy, to consist of two main phases Cu2SnS3 and Cu3SnS4 as well as of the secondary phase of Cu2 amp; 8722;xS. The electrical conductivity of the spray deposited p type CTS thin films under investigation is determined by two shallow acceptor levels Ev 0.07 eV at T lt; 334 K and Ev 0.1 eV at T gt; 334 K. The material of the CTS thin films was established to be a direct band semiconductor with the bandgap Eg 1.89 eV. The SEM and x ray energy dispersive analysis show the surface and cross section of the CTS thin film deposited onto molybdenum coated glass ceramics substrate with the actual atomic ratios of Cu Sn S being 2.9 1 2.64, which is in good agreement with the Raman spectra. Also, a small content of residual Cl atoms was found in the CTS thin films under investigation as the by product of the pyrolytic reaction

Thickness dependent structural parameters of kesterite Cu2ZnSnSe4 thin films for solar cell absorbers

The influence of thickness on the structural parameters, off stoichiometry and cation disorder in kesterite Cu2ZnSnSe4 films grown by flash deposition for solar cell absorbers is investigated employing X ray diffraction, energy dispersive X ray and Raman spectroscopies. It is shown that the lattice parameters of Cu2ZnSnSe4 changed depending on film thickness the 100 nm film turned out to be weakly stretched on the molybdenum coated glass substrates, while, in the thicker films, the compressive deformation is defined. The causes of the changes in film structure are outlined. Raman spectra revealed secondary phases like Cu2SnSe3 detecting reduction of its fraction with an increment in thickness; also, the SnZn antisite defect fraction decreases. Simultaneously, the share of disordered kesterite phase associated with CuZn antisite defects rises with thickness. The obtained results can be useful for optimization of technological growth proces