IMPROVEMENT IN IR PROPERTIES OF CHEMICALLY VAPOR-DEPOSITED DIAMOND FILMS BY SMOOTHENING WITH KRF EXCIMER RADIATION

Diamond films of different thicknesses (10-25 mum) were deposited on silicon substrates by d.c. arc discharge plasma jet chemical vapour deposition. The films were separated from the silicon substrate by dissolving the silicon in aqueous HF. Examinations of the obtained diamond films with scanning electron microscopy, X-ray diffraction and Raman spectroscopy have confirmed that the quality of the deposits is comparable with that of natural diamond. The films were irradiated with KrF excimer laser pulses of different fluences up to 3 J cm-2. The initial surface roughness of the diamond film was strongly diminished during the irradiation from pulse to pulse (10-50 nm pulse-1; fluence, 1.6 J cm-2). Unirradiated films have a very high electrical resistivity (rho > 10(8) OMEGA cm), while the resistivity of the irradiated films was reduced to about rho = 0.2 OMEGA cm (fluence, 1.6 J cm-2; 60 pulses), which is due to the probable conversion of diamond to graphite during laser irradiation of the films. The IR transmittance for unirradiated films varied with the wavenumber from about 2% near 4000 cm-1 to about 40% near 400 cm-1. After laser irradiation of the films, the transmittance was greatly enhanced. The transmittance of the irradiated films varied with the wave number from about 30% near 4000 cm-1 to about 60% near 400 cm-1.