In order to tailor diamond synthesized through chemical vapour deposition (CVD)
for different applications, many diamond films of different colours and variable
quality were deposited by a 5 kW microwave plasma CVD reactor under different
growth conditions. The morphology, quality and hydrogen incorporation of these
films were characterized using scanning electron microscopy (SEM), Raman and
Fourier-transform infrared (FTIR) spectroscopy, respectively. From this study, a general
trend between hydrogen incorporation and film colour, morphology and quality was found.
That is, as the films sorted by colour gradually become darker, ranging from
white through grey to black, high magnification SEM images illustrate that the
smoothness of the well defined crystalline facet gradually decreases and second
nucleation starts to appear on it, indicating gradual degradation of the crystalline
quality. Correspondingly, Raman spectra evidence that the diamond Raman peak at
1332 cm−1
becomes broader and the non-diamond carbon band around
1500 cm−1
starts to appear and becomes stronger, confirming increase of the non-diamond
component and decrease of the phase purity of the film, while FTIR spectra show
that the CH stretching band and the two CVD diamond specific peaks around
2830 cm−1
rise rapidly, and this indicates that the total amount of hydrogen incorporated into the film
increases significantly.