Pulsed-laser deposition of carbon: from DLC to cluster-assembled films

摘要: Abstract Carbon films have been synthesized on (100) Si substrates at room temperature by KrF Excimer Pulsed Laser Deposition (PLD) of highly oriented pyrolitic graphite. Changing laser power density (from 0.5 to 19 MW mm −2 ) and ambient conditions (vacuum; molecular nitrogen 1 Pa; helium, from 0.6 Pa 2 kPa), a range structures microstructures, DLC nanosized cluster assembled (CA) were obtained. The microstructure morphology the studied Scanning Electron Microscopy. surface all deposited in vacuum appears uniform, flat, featureless. In CA films, nature-pressure gas energy each pulse determine threshold fluences increasing value. These correspond sequence dense columns, followed nodule-like an open dendritic structure. Atomic Force Microscopy several allowed estimate size distribution relative abundancies aggregates carbon clusters. Film is correlated with ballistic mechanisms that occur when plasma plume constituents interact atoms. For local coordination was visible Raman spectroscopy. UV spectra collected for vacuum- nitrogen-deposited films. are hydrogen-free, as shown Fourier Transform Infra-Red spectroscopy, result invariably structurally disordered. Vacuum-deposited undergo transition mainly disordered graphitic up 80% tetrahedral amorphous (ta-C) above density. Transmission Energy Loss selected samples confirmed ta-C formation. same absent N atmosphere. All disordered, sp coordinated, belong family nanoglasses. underlying graphite discussed reference different atmospheres.