Static SIMS study on surfaces of chalcogenide glasses modified by an organic layer

Chalcogenide glasses are useful optic materials that find applications in infrared spectroscopy, sensors and thermal imaging. A route for direct surface modification of such glasses with organic layers has been investigated by static Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The GAS (germanium-arsenic-selenium) glasses are modified by deposition followed by UV-irradiation of disulfide- or/and silane-functionalized organic molecules. SIMS analysis shows the characteristic fragments of the grafted molecules and organic-inorganic fragments which prove unambiguously the binding mode to the surface: disulfides, after S-S cleavage, are linked to arsenic and selenium; triethoxysilanes bind exclusively to oxidized germanium. The successive grafting of disulfide and silane compounds on the same substrate (IG2 glass with 33% of Ge) affords a mixed organic layer on the glass surface. From water contact angle measurements and X-ray Photo-electron Spectroscopy (XPS), the coverage density is not significantly improved comparatively to the non-mixed layers. However, the grafting of both types of molecules allows to reach a more homogeneous coverage. (C) 2012 Elsevier B.V. All rights reserved.