Study on diamond films with ultra high nucleation density deposited onto alumina, sapphire and quartz

The poor adhesion between the diamond and sapphire is attributed to the weak interface interaction between the film and the substrate and to the difference in the coefficient of thermal expansion. On the other hand, it is suggested that the reason for good adhesion between diamond film and alumina substrate is that high carbon diffusivity onto alumina grain boundaries allows strong touch-points at the grooves of alumina grains, and this prevents the delamination of the diamond film. This adhesion mechanism, promoted by submicron diamond grain-size, is allowed due to initial high nucleation density. The Raman spectroscopy analysis shows a similar evolution tendency of diamond Raman peak frequency in the diamond films on alumina and quartz: intrinsic stress decreases as deposition time increases.