CHARACTERIZATION OF AMORPHOUS HYDROGENATED CARBON NITRIDE FILMS PREPARED BY PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION USING A HELICAL RESONATOR DISCHARGE

Amorphous hydrogenated carbon nitride thin films (a-CNx:H) have been p repared by plasma-enhanced chemical vapor deposition of N-2 and CH4 ga ses using a helical resonator discharge. The structural and optical pr operties of the deposited a-CNx:H films have been systematically studi ed as a function of the substrate temperature and radio frequency (rf) substrate bias. The chemical structure and elemental composition of t he a-CNx:H films were characterized by Fourier transform infrared spec troscopy (FT-IR), x-ray photoelectron spectroscopy (XPS), and Raman sp ectroscopy. The optical properties of the films were evaluated using t ransmission ultraviolet-visible spectroscopy. The morphology of the fi lms was investigated by scanning electron microscopy and atomic force microscopy. The FT-IR and XPS studies demonstrate the presence of carb on-nitrogen bonds with hydrogenated components in the films. The film composition ratio N/C was found to vary from 0.127 to 0.213 depending on the deposition conditions. The Raman spectra, showing the G and D b ands, indicate that the a-CNx:H films have a graphitic structure, It c an be found that the optical band-gap E-g of a-CNx:H films is associat ed with graphitic clusters, while the decrease in E-g is correlated wi th an increase in the size and number of graphitic clusters. Combining the results of Raman and optical measurements, it can be concluded th at a progressive graphitization of the films occurs with increasing th e substrate temperature and rf substrate bias power, corresponding to bias voltage. (C) 1997 American Institute of Physics.