Correlation study of structural, optical and electrical properties of amorphous carbon thin films prepared by ion beam sputtering deposition technique

The correlation of structural, optical and electrical properties of amorphous carbon thin films deposited by ion beam sputtering technique on the glass substrate was investigated. The film thickness varied over a wide range from 57 to 408 nm by controlling the deposition time. Raman spectra and X-ray photoelectron spectroscopy showed that the size of the graphite crystallites with sp2 bonds (La) and the sp3/sp2 fraction are smaller than 1.5 nm and 1.4, respectively. The values of ID/IG ratio, the 'G' peak position, and surface roughness depend on the film thickness; all of them increased by increasing film thickness up to 360 nm, and then decreased by increasing time and thickness. Furthermore, the resistivity followed similar trends of these structural properties. According to Tauc equation the optical band gap of these films was in the range of 3.2-3.9 eV. A broad emission peak at around 2.94 eV was observed on a photoluminescence spectrum of amorphous carbon film with highest resistivity.