Liquid gas was used to produce DLC films on Cu, Al and steel substrates by DC plasma technique. The absorption in IR reflectance indicates, grown films are DLC. By deconvolution of room temperature UVvisible spectra of the films grown at 50 mtorr and 200 • C, in addition to the spectra lines reported for CL, PL, PLC and ESR, some new spectra lines were obtained. We also, have seen exciton absorption line at room temperature.PACS number: 71.35.C, 78.40, 81.05.T, 78.66, 61.72.J Typeset using REVT E X * e-mail address: vesaghi@physic.sharif.ac.ir † e-mail address: ashafie@theory.ipm. [9], were used to make DLC and a-C:H films. The gases which are used in most of these deposition methods are C 2 H 2 , CH 4 and C 2 H 6 pure or mixed with hydrogen. In all these techniques neutral or ionized atoms of carbon or various hydrocarbon precursor ions have been produced. These species with free (dangling) hand reach substrate, and those with sufficient time and energy stick to substrate and to each other.It is now well understood that films deposited by these techniques are amorphous or diamond-like carbon with no-long range order in structure. Because of the non-equilibrium nature of the growth, there must be some vacancies in these films [5]. These vacancies are produced by the impact of the ions reaching the growth surfaces with sufficient energy, sputtering off weak bonded species or damaging these surfaces. Also, there are vacancies in the domain-walls of the microcrystals. The vacancies at the surface of substrate with film are less important since the area of this surface is much smaller than total area of domain-walls. The quality of the film is dependent on the nature and the numbers of these defects. If one understands the nature of such defects and is able to control their numbers, one would be able to control the film quality and to use them as a source for coherent luminescence and other purposes.Cathodoluminescence (CL) [10,11], photoluminescence (PL) [2,6], positron-life time spectroscopy (PLS) [12] and electron-spin resonance (ESR) [13] methods are used for vacancy identification.The aim of this work is to show the possibility of making DLC films from liquid gas on metallic substrates and to obtain information about vacancies from UV-visible reflectance of DLC films.Carbon films were deposited on polished 2 × 3cm copper, steel and aluminium substrates from liquid gas (60% Butane and 40% Propane) by dc plasma technique. The substrate temperature was 200 • C and it was grounded. The chamber was flashed from 1 mtorr three times prior to deposition. The pressure and the gas flow were kept constant during deposition. Saturation voltage was applied to anode. Double beam Perkin-Elmer UV-visible spectrometer was used to measure the reflection and absorption of the films. The angle of incident beam was 6 • and measurements were done at room temperature. IR spectra was obtained at room temperature by Perkin-Elmer IR spectrometer.
FIGURESFIG. 1. Room temperature IR spectra in a reflective mode for DLC film de...