XPS study of Ge-Se-Te surfaces functionalized with organosilanes

Amorphous Ge25Se55Te20 chalcogenide thin films have been functionalized with three organosilanes: (3-ami-nopropyl)triethoxysilane, tetraethoxysilane and a mixture of tetraethoxysilane and octyl-trimethoxysilane. The functionalized films have been studied by X-ray photoelectron spectrometry, providing an interesting insight of the surface modification process and chemistry. First, the calculated stoichiometric ratios oxygen/silicon, car-bon/silicon and nitrogen/silicon are in good agreement with the theory, demonstrating the effectiveness of the functionalization and relative precursors homocondensation. Secondly, the deconvolution of the 3d5/2 and 3d3/2 tellurium orbitals before and after functionalization show new oxidized environments. More specifically, the simultaneous disappearance of the bands at 573.0 eV and 583.4 eV attributed to Te-Ge and Te-Te bonds (resp.) and appearance of a Te-O environment (around 576.5 eV and 587.0 eV) strongly suggest covalent anchorage of the three precursors thanks to the formation of new Te-O-Si groups. This is the first report on tellurium anchorage of organosilane precursors onto chalcogenide surface.