A significant improvement in surface morphology of ultrananocrystalline diamond (UNCD) film was achieved with hydrogen heat treatment of nanodiamond (ND) seed particles. By hydrogen heat treatment, the average size of ND aggregates was greatly reduced from ∼2 µm to ∼55 nm as the ND surfaces were modified to hydrogen-containing functionalities. Si surfaces seeded with the hydrogen heat-treated ND seeds showed very high seeds densities up to ∼1011 cm−2. The grown UNCD film with ND seeds treated at 600 °C provided a very smooth surface morphology consisted of small and uniformly distributed grains compared to the film grown with untreated ND seeds.
AFM scan image of the grown UNCD films seeded with untreated and hydrogen heat-treated ND particles.