The structure of tetrahedral amorphous carbon thin films
Tetrahedral amorphous carbon (ta-C) thin films were deposited using both the filtered cathodic vacuum arc (FCVA) and the pulsed laser arc (PA) deposition techniques. The FCVA deposited films are analysed as a function of ion energy of the deposition species and substrate temperature. The films deposited using FCVA as a function of temperature are compared with those deposited using the PLA technique. The microscopic structure of the films is examined using electron microscopy. The density, bonding hybridization and chemical composition are obtained by electron energy loss spectroscopy (EELS). The data for the diamond-like sp3 bonding component in the ta-C film clearly show a peak which is predicted by the subplantation models proposed for the growth of amorphous carbon films. The structural modifications observed as a function of temperature can also be explained using the subplantation model. Under certain deposition conditions used in this study, nanocrystallites are observed embedde d in the amorphous carbon matrix. The chemical composition of these crystallites is carbon. The microstructure of the deposited crystals is analysed in terms of lattice spacing and is indexed to graphite and cubic diamond.