Role of nucleation in nanodiamond film growth

Nanodiamond films were deposited using different microwave plasma chemical vapor deposition schemes following several nucleation pretreatment methods. The nucleation efficiency and the films structure were investigated using scanning and transmission electron microscopy and Raman spectroscopy. C2 dimer growth (C H4 and H2 in 90% Ar) cannot nucleate diamond and works only on existing diamond surfaces. The methyl radical process (up to 20% C H4 in H2) allows some nucleation probability on appropriate substrates. Prolonged bias enhanced nucleation initiates both diamond nucleation and growth. C2 dimer growth results in pure nanodiamond free of amorphous carbon, while prolonged bias enhanced nucleation forms an amorphous carbon/nanodiamond composite. © 2006 American Institute of Physics.