X-ray absorption study of diamond films grown by chemical vapor deposition

Carbon k-edge x-ray absorption fine structure (XAFS) is used to study the structure and bonding of chemical vapor deposition (CVD) grown diamond and diamond-like carbon films. Diamond films grown at 875 °C on silicon using a 1% CH4 /H2 mixture have near-edge spectra resembling type 1(a) natural diamond. The k-edges of the diamond-like films grown by electron cyclotron resonance CVD at 200 °C using 10−4 Torr of CH4 show a broad main peak lacking the sharp structure of graphite or diamond. Comparing the near edges of the CVD diamond film with other carbon compounds (i.e., graphite) and the CVD diamond film, the diamond-like film shows a strong π* feature at 285 eV indicative of sp2 bonded carbon and a feature at 289 eV, the σ*(C–H) resonance indicating C–H bonds. The relatively weak extended x-ray absorption fine structure (EXAFS) shows that the diamond-like carbon film is highly disordered on an atomic level.