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Vilma Buršíková, Pavel Rehulka, Josef Chmelik, Milan Alberti, Z Spalt, Jan Janča, Josef Havel

Laser ablation time-of-flight mass spectrometry (LA-TOF-MS) of ``nitrogen doped diamond-like carbon (DLN) nano-layers

Journal of Physics and Chemistry of Solids 68 (2007) 701-706

Nitrogen-doped diamond-like carbon (DLC) layers (a-C:H:N, N-DLC or DLN) were prepared by the plasma-enhanced chemical vapor deposition (PECVD) technique, using a RF capacitive discharge (13.56 MHz), at low pressures (20 Pa), produced from a mixture of methane, nitrogen and hexamethyldisiloxane (HMDSO), deposited on single-crystalline silicon wafers placed on steel samples. The films, of differing deposition times, were subjected to laser ablation time-of-flight (LA-TOF) mass spectrometric measurements, using different commercial instrumentation to characterize their structures. The analysis of mass spectra was made and the following positively singly charged species were detected and identified: C-n(+) (n = 4-30), Si-n(+) (n = 2, 3), SinH (+)(n = 2, 3), SiOK (+), Si3H4+, Si2N+, Si2NH2+ 2 and Si3C+. The later three species could reflect the presence of nitrogen-silica and carbon-silica chemical bonds in the structure of the DLN layer. The stoichiometry of all species was confirmed by isotopic pattern simulation. In the negative detection mode, the C-n(-) (n = 2-12) clusters were observed. The findings are discussed in the light of the current research concerning analysis of the DLN thin layers and it is concluded that namely Si2N+, Si2NH2+ and Si3C+ species are reflecting the chemical structure of the DLN layer. LA-TOF-MS was found useful supplementary method for the characterization of DLN nano-layers.

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Cited Articles

  1. Buršíková V., Zajíčková L., Dvořák P., Valtr M., Buršík J., Bláhová O., Peřina V., Janča J.,
    Influence of Silicon, Oxygen and Nitrogen Admixtures Upon the Properties of Plasma Deposited Amorphous Diamond-Like Carbon Coatings,
    Journal of Advanced Oxidation Technologies 9 (2006) 232–236