Diamonds were successfully nucleated on SiO2-coated silicon substrates using a high power microwave plasma enhanced chemical vapor deposition process. Nucleation rates on SiO2surfaces (i.e., 0.5×1010cm−2) were, however, still smaller than those on Si surfaces (i.e., 1.0×1010cm−2). The major advantage in using high power microwaves was revealed by optical emission spectroscopy to be that the atomic C and H species produced are more abundant and energetic. Therefore, the negative bias effect is enabled and the formation of sp3bonds is enhanced. The nucleation of diamonds on SiO2surface is thus made possible. The growth of diamonds behaved similarly on the prenucleated surface, regardless of the nature of the substrates. Diamonds were of single grain columnar structure with random orientation when deposited without bias and were of multi-grain columnar structure with [111] or [001] preferred orientation when deposited under −100 V dc bias. Multi-grain columnar structure was ascribed to the induction of secondary nucleation at the presence of bias voltage. ©1997 American Institute of Physics.