Abstract
This letter describes the fundamental process underlying the synthesis of ultrananocrystalline diamond (UNCD) films, using a new low-pressure, heat-assisted bias-enhanced nucleation (BEN)/bias enhanced growth (BEG) technique, involving H2 C H4 gas chemistry. This growth process yields UNCD films similar to those produced by the Ar-rich/ C H4 chemistries, with pure diamond nanograins (3-5 nm), but smoother surfaces (∼6 nm rms) and higher growth rate (∼1 μmh). Synchrotron-based x-Ray absorption spectroscopy, atomic force microscopy, and transmission electron microscopy studies on the BEN-BEG UNCD films provided information critical to understanding the nucleation and growth mechanisms, and growth condition-nanostructure-property relationships. © 2008 American Institute of Physics.