Photochemical Deposition of ZnS From Gas Phase and Simultaneous Luminescence Detection of Photofragments from a Single source Precursor Zn[S$_2$COCGMe$_2$]$_2$

Abstract

ZnS thin films are made by laser driven chemical vapor deposition (CVD) from a single-source precursor, Zn(S(2)COCHMe(2))(2) under vacuum conditions. Photofragments in the gas phase are identified simultaneously by luminescence spectroscopy. The laser selectively activates the initial decomposition of the precursor and drives its conversion to the desired materials under mild conditions. These photolytically produced films are compared to films made by thermal deposition from the same precursor. The deposits from both techniques, characterized by X-ray diffraction, Rutherford backscattering, and X-ray photoelectron spectroscopy, are pure stoichiometric ZnS in the hexagonal phase. Surface morphology differs in shape and granule size. During the laser-driven CVD process, gas-phase photochemical intermediates are identified by luminescence spectroscopy. The luminescent photoproducts are Zn and S-2, the two elemental components of the final material. Photofragmentation mechanisms leading to ZnS, the luminescent species Zn and S-2, and the gaseous organic byproducts are discussed. Further characterization of the photofragmentation pathways is provided by the trapping of the photoreaction products and by mass spectroscopy.