Adsorption and reactivity of nitrogen atoms on silica surface under plasma exposure

作者：Marinov D^*; Guaitella O; de los Arcos T; von Keudell A; Rousseau A

来源：Journal of Physics D: Applied Physics , 2014, 47(47): 475204.

DOI：10.1088/0022-3727/47/47/475204

• adsorption and recombination of atoms
• plasma-surface interactions
• isotopic exchange on surfaces
• nitridation
• XPS

The kinetics of adsorption, desorption and recombination of nitrogen atoms on a silica surface is investigated. Stable nitrogen atoms are grafted to the inner surface of a fused silica discharge tube by a discharge in N-2 at 0.53 mbar. After the pre-treatment, the surface is analysed using x-ray photoelectron spectroscopy and an isotopic exchange technique. The latter consists of the exposure of the pre-treated surface with a discharge in the heavy nitrogen isotope N-30(2). Nitrogen isotopologues N-29(2) and N-28(2) produced on the surface are detected using a mass spectrometer and provide information about the coverage and reactivity of adsorbed N-14 atoms. It is found that during the pre-treatment, a silicon oxynitride (SiOxNy) layer is formed on the initially clean SiO2 surface. The coverage of N on the surface increases from 5 x 10(13) to 5 x 10(15) cm(-2) for a pre-treatment duration in the range of 10(-2) - 10(4) s. Atoms on the surface demonstrate a distribution of reactivity, which is attributed to a distribution of their binding energies and configurations on the surface. We demonstrate that stable chemisorbed N-ads are not the main recombination sites for N atoms on the surface contrary to previous studies. We conclude that recombination takes place mainly on weakly bonding active sites with the binding energy smaller than 1 eV.

• 出版日期2014-11-26