PHYSICAL-PROPERTIES OF THIN CARBON NITRIDE FILMS DEPOSITED BY ELECTRON-CYCLOTRON-RESONANCE ASSISTED VAPOR-DEPOSITION

Electron cyclotron resonance (ECR) plasma-assisted vapor deposition has been used to grow thin carbon nitride films on Si(100) and sapphire substrates. The composition, structure, and optical properties of the films were investigated by x-ray photoelectron spectroscopy (XPS), Rutherford backscattering (RBS), Raman, and optical absorption spectroscopies. The effect of varying the nitrogen gas flow, at constant substrate temperature and carbon deposition rate, on the C/N composition ratio and the CxNy crystal structure was investigated. From both RBS and XPS, the nitrogen concentration in the film was found to be in the range of 20%-48% and varied directly with the nitrogen partial pressure in the ECR source. In CN films with low nitrogen content, the Raman spectra showed no evidence of CN bonding and were characteristic of graphitic carbon. In contrast, the Raman spectra of high nitrogen content thin films show a wide peak at 1291 cm-1, suggesting the formation of a CxNy phase with predominately sp3bonding. The optical band gap of CN films deposited on sapphire was found to be about 1.95 eV, which is below that reported for amorphous CN films, suggesting a higher structural order. © 1995, American Vacuum Society. All rights reserved.