The effect of low temperature thermal treatment on structural and chemical composition of a-C film with nc-G admixture studied by Raman spectroscopy

• Published in: Diamond and related materials 2019-05, Vol.95, p.44-54
• Main Authors: Dychalska, Anna, Fabisiak, Kazimierz, Paprocki, Kazimierz, Koczorowski, Wojciech, Trzcinski, Marek, Szybowicz, Mirosław
• Format: Article
• Language: English
• Subjects: Admixtures; Amorphous structure; Annealing; Banded structure; Carbon; Chains; Chemical composition; Cooling; Graphite; Heat treatment; Low temperature; Nanocrystals; Organic chemistry; Photoelectrons; Raman spectroscopy; Scanning electron microscopy; Spectroscopic analysis; Spectrum analysis; X ray photoelectron spectroscopy
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2019.03.016

Extensive Raman spectroscopy studies combined with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were applied to investigate structural changes in amorphous carbon film upon its annealing to 300 °C and cooling. The results show the variation in the carbon structure within the sample and the presence of nanocrystalline graphite features, as well as minor inclusion of sp1 linear chains. The studies on the behaviour of characteristic D and G bands upon annealing to 300 °C and cooling reveal structural changes in amorphous carbon (a-C) as well as nanocrystalline graphite (nc-G). The intensity ratio ID/IG, FWHM and position of the G band indicates irreversible structural ordering of a-C annealed to 300 °C, which is also confirmed by XPS measurements. Additionally, Raman spectrum of nc-G is decomposed into 4 bands D1, D2, G1, G2 and similar behaviour of G2 band's parameters is observed. SEM measurements reveal a-C aggregates of spherical structures, however before annealing the smallest counterparts of these structures resemble chains, which is also supported by the presence of sp1 features in the Raman and XPS spectra. [Display omitted] •Amorphous carbon film deposited by arc evaporation method includes inclusion of nanocrystalline graphite and sp1 carbon chains.•Annealing to 300 °C lead to irreversible ordering of amorphous carbon structures.•Sp1 carbon chains survived annealing in air up to 200 °C.•Sp1 carbon and/or SiC was identify in C1s peak of XPS spectra as a band with low intensity at 283.5 eV.