Lexi Shao

Cu2ZnSnS4 thin films prepared by sulfurization of ion beam sputtered precursor and their electrical and optical properties

Cu2ZnSnS4 (CZTS) thin films were successfully prepared by sulfurization of ion bean sputtered precursors on soda-lime glass substrate. The single phase of stannite-type structure CZTS films were obtained as revealed in EDS and XRD analysis when the ratios of the constituents of CZTS thin films are close to stoichiometric by optimizing the conditions of precursor preparation and sulfurization. A low sheet resistivity as about 0.156 Ω·cm and a high absorption coefficient as 1×104 cm-1 were achieved in this method by Hall effect measurements and UV-VIS spectrophotometer. The optical band-gap energy of the CZTS sample is about 1.51 eV, which is very close to the optimum value for a solar-cell absorber.

Characterization and Mechanical Properties of Ti–Al–Cr–N Nanocomposite Coatings Deposited by Closed Field Unbalanced Middle Frequency Magnetron Sputtering

Ti?Al?Cr?N coatings, characterized by a nanocomposite comprising nano-sized TiN crystallites embedded in amorphous AlN or CrN matrix, could be successfully synthesized on Si(111) and WC?Co cemented carbide substrates by a closed field unbalanced middle frequency magnetron sputtering method. The Cr content in the Ti?Al?Cr?N coatings linearly increased from 11.2 to 32.8 at. % raising the Cr targets currents from 5 to 15 A, whereas the Ti content decreased from 63 to 47 at. %. The high resolution transmission electron microscope (HRTEM) image and diffraction patterns clearly show that the Ti?Al?Cr?N coatings were composites of crystallites and amorphous phase, which were distinguished from each other by lattice fringe contrast. The hardness and Youngs modulus value of the Ti?Al?Cr?N coatings increased with incorporation of Cr, and had the maximum value of 38.9 and 475 GPa at the Cr content of 17 at. %, respectively. The average friction coefficient of the Ti?Al?Cr?N coatings largely decreased with an increase of the Cr content when compared to the TiN coatings.