Chemical depth profile of layered a-CSiO:H nanocomposites

• Published in: Applied surface science 2018-10, Vol.456, p.941-950
• Main Authors: Houdkova, Jana, Branecky, Martin, Plichta, Tomas, Jiricek, Petr, Zemek, Josef, Cech, Vladimir
• Format: Article
• Language: English
• Subjects: Argon gas cluster ion beam; Layered nanocomposite; Plasma-enhanced chemical vapor deposition; Post-deposition oxidation; XPS depth profiling; Young’s modulus
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2018.06.227

[Display omitted] •Layered nanocomposites with controlled distribution of mechanical properties.•XPS depth profiling using argon gas cluster ion beams.•Post-deposition oxidation of oxygen-free and oxygen-bound layers.•Oxygen-bound layer behaved as an oxygen diffusion barrier.•Identical bonding states in oxygen-bound and oxidized layers. Layered nanocomposites with a controlled distribution of mechanical properties across the nanostructure were constructed from oxygen-free (a-CSi:H) and oxygen-bound (a-CSiO:H) individual layers. These were deposited at different power or pulse periods from pure tetravinylsilane and tetravinylsilane in a mixture with oxygen gas using plasma-enhanced chemical vapor deposition operating in pulse mode. XPS depth profiling using argon gas cluster ion beams was used to determine the atomic concentration of carbon, silicon, and oxygen in the individual layers forming the nanocomposite. These layers had a total thickness of about 100 nm. The XPS analysis revealed that the oxygen-free layers were oxidized due to post-deposition oxidation in the ambient air. Oxygen was even diffused in an oxygen-bound layer, which was confirmed by repeated XPS depth profiling within three months after nanocomposite deposition. The upper oxygen-bound layer at the nanocomposite surface behaved as a barrier and reduced oxygen diffusion. The high energy-resolution XPS spectra (C 1s, Si 2p, and O 1s) were analyzed to gain more insight into bonding species formed in layered nanocomposite. This detailed analysis showed that oxygen atoms originating from the ambient air were bound in the oxidized a-CSi:H layers and formed the same bonding states as those in the as-deposited oxygen-bound layers.