Influence of in-process copper incorporation on the quality of diamond-like carbon films deposited by pulsed laser deposition technique

Abstract

Copper-incorporated carbon films have been prepared on Si(100) and Corning (7059) glass substrates by the pulsed excimer laser deposition technique using KrF radiation (λ = 248 nm). Cold-pressed composite pellets, having compositions from 2 at. % to 11 at. % copper in carbon, were used as targets for ablation. Good quality, scratch-proof films were obtained at a laser energy density of 2−3 J/cm2 and a substrate temperature of 50 °C. The films were characterized by x-ray diffraction (XRD), Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), UV-visible spectrometry, ellipsometry, and four-point probe resistivity measurements. Under similar deposition conditions, films obtained from composite targets of lower copper concentration are seen to have better diamond-like character as compared to those obtained from a pure graphite target. At such low concentrations, copper is seen to cluster in the form of nanoparticles. As the copper concentration increases in the films, they tend to acquire disordered graphitic network with degraded DLC characteristics, and the size of copper agglomerates increases from about 5 nm (for the 2 at. % case) to 85 nm (for the 11 at. % case). It is seen that an increase in the copper content leads to modifications in the carbon network, additional interband transitions, and reduction of the band gap.

Atomic structure, electrical properties, and infrared range optical properties of diamondlike carbon films containing foreign atoms prepared by pulsed laser deposition

“…Four-probe measurements showed that the resistance of the DLC films does not change linearly with dopant concentration, 30 in agreement with that in Ref. 31. Amorphous semiconductors usually have all states localized, and their conduction exhibits hopping, especially variablerange hopping mechanism.…”

“…The first regime corresponds to large wave numbers (higher photon energies) that shows high emittance. Though DLC films prepared by 248-nm excimer laser with high laser fluence (∼10 J/cm 2 ) have been reported to have a band gap of ∼1.5 eV, Dikshit et al 31 reported a value close to 1.0 eV on DLC films prepared under the same laser fluence as the present work. We may therefore attribute the first regime to band-to-band transitions.…”

Self-Organized Formation of Metal-Carbon Nanostructures by Hyperthermal Ion Deposition

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Over the past two decades, there has been a considerable amount of research about the structure and structure formation of metal-containing diamond-like carbon thin films, which is, of course, mainly due to the promising potential in the various fields of application mentioned above. There are a number of methods that are used for the preparation of carbon films containing metal nanoparticles, including pulsed laser deposition [28,29], integrated nanocluster deposition [30], filtered cathodic vacuum arc deposition [31,32], ion beam co-sputtering [33,34,35], and DC [36,37] and RF magnetron sputtering [38,39].The analyses performed on metal-containing amorphous carbon films, of course, depend on the field of application that the researchers are aiming at. A number of the above groups investigate the influence of the metal on the tribological properties of the films [31,32,38], while others focus on the behaviour of the metal within the films, i.e.

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“…Over the past two decades, there has been a considerable amount of research about the structure and structure formation of metal-containing diamond-like carbon thin films, which is, of course, mainly due to the promising potential in the various fields of application mentioned above. There are a number of methods that are used for the preparation of carbon films containing metal nanoparticles, including pulsed laser deposition [28,29], integrated nanocluster deposition [30], filtered cathodic vacuum arc deposition [31,32], ion beam co-sputtering [33,34,35], and DC [36,37] and RF magnetron sputtering [38,39].…”