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The deposition rate and thickness evolution of the nondiamond (sp2-bonded) carbon volume fraction in very thin, but fully coalesced, nanocrystalline diamond films produced on Si substrates by microwave plasma-enhanced chemical vapor deposition from gas mixtures of CO and H2, were determined by real time spectroellipsometry. A broad subsidiary minimum in the sp2 C content was found, centered near a CO/H2 ratio of 2, corresponding to the C-H-O diamond-growth phase-diagram coordinate of about 0.5. Under these gas flow conditions, the deposition rate is a complicated function of temperature, having a peak near 550 degrees C.

Real time spectroscopic ellipsometry (SE) was used to characterize diamond nucleation by filament assisted chemical vapor deposition. The use of SEin turn led to improved control over interface contamination, substrate temperature and nuclei induction time. In addition, SE monitors interface structure and mass thickness evolution associated with the discontinuous particle film. The results show the effectivity of the use of ellipsometric methods for thin film nucleation characterization.

In this letter it is shown that vapor deposited thin films prepared under conditions of low adatom mobility, such as amorphous Ge films in the present study, exhibit a nonlinear decrease in void fraction, and hence an increase in density with increasing film thickness. Fractal modeling of the internal void network structure in this class of vapor deposited films shows that the void boundaries define the surfaces of growth cones and these voids are, in general, not expected to be distributed uniformly with film thickness. [ABSTRACT FROM AUTHOR]