Sj. Harris et al., DIAMOND FILM QUALITY - EFFECTS OF GAS-PHASE CONCENTRATIONS ON THE RAMAN-SPECTRA, Journal of applied physics, 80(4), 1996, pp. 2187-2194
A series of diamond films have been grown, all at T-sub=1110 K and ato
mic H concentrations [H]=3x10(-10) mol/cm(3). The acetylene and methyl
radical concentrations at the substrate surface were varied independe
ntly by factors of up to 4 and 10, respectively, by adjusting the pres
sure and the input methane concentration, and the effects of these var
iations on the Raman spectra were examined. The linewidth of the 1332
cm(-1) diamond feature, the sp(2) nondiamond carbon feature, and the l
uminescence yields all increased with increased [CH3](sub), but varyin
g the [C2H2] had no observable impact. A quantitative relationship is
provided between the sp(2) content and [CH3](sub). The luminescence pe
ak, which is the most sensitive feature to [CH3](sub), is due to an im
purity from the filament. Using micro-Raman spectroscopy, large variat
ions are found in the Raman spectra of adjacent crystals and within a
single crystal. We attribute these fluctuations to inhomogeneous and a
nisotropic strains. (C) 1996 American Institute of Physics.