Quantitative Relation betweenthe Hamaker Constant and the Water Contact Angle with sp2/sp3 Ratio and Hydrogen Content in a Hydrogenated Diamond-Like Carbon Thin Film

Authors Hari Shankar Biswas

Department of Chemistry, Surendranath College, 24/2, Mahatma Gandhi Road, 700009 Kolkata, India

Е-mail harishankarb7@gmail.com
Issue Volume 14, Year 2022, Number 3
Dates Received 24 March 2022; revised manuscript received 22 June 2022; published online 30 June 2022
Citation Hari Shankar Biswas, J. Nano- Electron. Phys. 14 No 3, 03008 (2022)
DOI https://doi.org/10.21272/jnep.14(3).03008
PACS Number(s) 52.50.Qt, 61.82.Rx, 68.55. − a
Keywords Diamond-like carbon, AFM (18) , SEM (112) , Contact angle (2) , sp2/sp3 ratio, Hamaker constant.

Allotropes of two crystalline carbons, diamond and graphite, are sp3 and sp2 hybridized, respectively. In between these two, there is an intermediate structure i.e., the mixture of sp3 and sp2 nanocrystalline hydrogenated diamond-like carbon (HDLC) thin films. HDLC thin films were synthesized by the biased enhanced nucleation (BEN) technique in the reactive gas-plasma process (RGPP) under the varying ratio of H2 and CH4 flow rates. There are numerous applications of these materials depending on their sp2/sp3 ratio and surface properties. The property, hydrophilic/hydrophobic nature of the film surfaces can be measured from the water contact angle on the HDLC surfaces easily which also depends on the sp2/sp3 ratio. In this paper, we have evaluated the sp2/sp3 ratio indirectly through the water contact angle of the HDLC thin film and under its annealing treatment at low pressure. The sp2/sp3 ratio and C1s bonding type were estimated by the XPS spectrum. The study of the surface topography of the HDLC film was made by AFM and SEM. In this study, it can be concluded that the water contact angle on the HDLC surface does not significantly affect the surface morphology. A quantitative relationship is found between the sp2/sp3 ratio and the water contact angle of HDLC with hydrogen content, measured by the Angus and Jansen equation, and the Hamaker constant estimated by AFM using different models.

List of References