Micro-Raman analysis of the cross-section of a diamond film prepared by hot-filament chemical vapor deposition

Raman micro-spectroscopy using exciting light with an approximately 2-mu m diameter exciting spot was undertaken to investigate the micro-structure of cross-section of a 100-mu m thick diamond film prepared by hot-filament ch emical vapor deposition (HFCVD). The Raman spectra exhibited different feat ures with changing position, suggesting that the composition of crystalline diamond, amorphous carbon and graphitic phases varied in the HFCVD process . The presence of a broad band and high background intensity in the spectra near the substrate surface was attributed to the amorphous carbon synthesi zed in the nucleation process of the film. A decreasing proportion of sp(2) -bond structure in the amorphous carbon phase with increasing film thicknes s was believed to account for the decline in the intensity of the 1200-1600 -cm(-1) band. The different composition of the diamond grains and of the gr ain boundaries in the him was shown in the Raman spectra obtained from diff erent positions at the same cross-sectional thickness by scanning the excit ing light parallel to the surface of the film. (C) 2000 Published by Elsevi er Science S.A. All rights reserved.