Research

January 1997

Photochemical Deposition of ZnS from the Gas Phase and Simultaneous Luminescence Detection of Photofragments from a Single-Source Precursor, Zn(S2COCHMe2)2

Posted by David Talaga

ZnS thin films are made by laser driven chem. vapor deposition (CVD) from a single-source precursor, Zn(S2COCHMe2)2 under vacuum conditions. Photofragments in the gas phase are identified simultaneously by luminescence spectroscopy. The laser selectively activates the initial decompn. 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 XPS, are pure stoichiometric ZnS in the hexagonal phase. Surface morphol. differs in shape and granule size. During the laser-driven CVD process, gas-phase photochem. intermediates are identified by luminescence spectroscopy. The luminescent photoproducts are Zn and S2, the two elemental components of the final material. Photofragmentation mechanisms leading to ZnS, the luminescent species Zn and S2, and the gaseous org. byproducts are discussed. Further characterization of the photofragmentation pathways is provided by the trapping of the photoreaction products and by mass spectroscopy.