Homogeneity of sol-gel derived silica-titania waveguide films – Spectroscopic and AFM studies
Authors:
- P. Karasiński,
- A. Domanowska,
- E. Gondek,
- A. Sikora,
- C. Tyszkiewicz,
- M. Skolik
Abstract
The aim of the present work was to investigate the influence of textures consisting of Laser-Induced Periodic Surface Structures (LIPSS) on the friction coefficient of silicon under unlubricated conditions, using nanoscale friction tests. The tests were performed on 〈1 1 1〉 single crystal wafers of p-doped silicon. Surface texturing was performed by a direct writing technique, using 560 fs pulses of 1030 nm wavelength radiation and parameters allowing large areas with a uniform LIPSS texture to be obtained. The tribological tests were performed in air using a ball-on-flat nanotribometer with 3 mm diameter sapphire balls as counterbodies. The wear scars were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The friction coefficient of polished Si remains approximately constant during the tests and is independent of the applied load, with values in the range 0.12–0.14. The morphology of the wear scars indicated that the predominant material removal mechanism is mild oxidative wear, independently of the testing conditions used, which explains the low values of the friction coefficient measured. The LIPSS texture leads to an increase of the friction coefficient, in particular in the perpendicular sliding direction. The friction coefficient increases with the applied load and is larger for the perpendicular sliding direction than for the parallel sliding direction, the difference increasing with increasing load. The morphology of the wear scars showed that the predominant wear regime remains oxidative wear, but significant contributions of plastic deformation and ploughing appear. This plastic deformation in Si, which is brittle at room temperature, shows that significant surface heating is being caused by the interaction of the asperities in motion and under load. This temperature increase also accelerates surface oxidation and increases the wear rate. Surface temperature calculations showed that the temperature increase is larger for the perpendicular sliding direction than for the parallel one, which explains the difference of friction coefficient observed in the two directions.
- Record ID
- CUT0877f7675dfd4a82a2570732c8126b41
- Publication categories
- ;
- Author
- Journal series
- Optics and Laser Technology, ISSN 0030-3992, e-ISSN 1879-2545
- Issue year
- 2020
- Vol
- 121
- Pages
- 1-8
- Article number
- 105840
- Other elements of collation
- fot.; schem.; tab.; wykr.; Bibliografia (na s.) - 7-8; Bibliografia (liczba pozycji) - 42; Oznaczenie streszczenia - Abstr.; Numeracja w czasopiśmie - Vol. 121
- Keywords in English
- optical homogeneity, planar waveguide, reflectance spectra, silica-titania film, sol-gel, transfer matrix 2×2 method
- DOI
- DOI:10.1016/j.optlastec.2019.105840 Opening in a new tab
- URL
- https://www.sciencedirect.com/science/article/pii/S003039921930636X Opening in a new tab
- Language
- eng (en) English
- Score (nominal)
- 100
- Additional fields
- Indeksowana w: Web of Science, Scopus
- Uniform Resource Identifier
- https://cris.pk.edu.pl/info/article/CUT0877f7675dfd4a82a2570732c8126b41/
- URN
urn:pkr-prod:CUT0877f7675dfd4a82a2570732c8126b41
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