OPTICAL AND STRUCTURAL PROPERTIES OF NITROGENATED DIAMOND-LIKE CARBON FILMS PREPARED BY r.f. PECVD

Abstract

Nitrogenated diamond-like carbon films have been deposited on glass and p-type Si (100) substrates by radio frequency (r.f.) plasma-enhanced chemical vapor deposition (PECVD) with a frequency of 13.56 MHz at room temperature using CH 4 as precursor of carbon source and H 2 as a carrier gas. The deposition was performed at a different flow rate of nitrogen from 0 to 12 sccm under a constant r.f. power. The effect of nitrogen incorporation on the bonding states and growth kinetics of the deposited films have been investigated by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy and optical properties by UV spectroscopy measurement. Our experimental results show that the incorporation of nitrogen has a considerable effect on the properties of the deposited films. FTIR spectra show that the nitrogen is bonded to carbon and hydrogen as C=N , C≡N , N–H and C–H bonding configurations in the as-deposited film. The incorporation of nitrogen is found to shift the Raman G peak toward the higher wave number and to increase the Raman I D /I G ratio demonstrating the graphitic character of the hydrogenated amorphous carbon–nitrogen films. Band gap is found to reduce with the increase in nitrogen concentration.