Published online by Cambridge University Press: 26 February 2011
The technology of low pressure chemical vapor deposition (CVD) of polycrystalline diamond films has advanced substantially in recent years [1–3]. However, fundamental understanding of the chemistry and physics occurring in this CVD process is still lagging. Although the key role that H atoms play in diamond CVD has long been recognized [4–6], the identity of the gaseous diamond precursors and the mechanism by which diamond is formed are still unclear. Only recently has interest in these critical issues grown. For example, theoretical predictions and quantum mechanical calculations of gas-solid reaction paths involving CH3 and CH3 + [7] or C2H2 [8] have been reported, and the thermodynamic analyses of diamond CVD processes have been examined [9,10]. In addition, experimental results and chemical models [11–16] have been presented in attempts to support specific species as the essential precursors of diamond growth. Nevertheless, no consensus has been reached concerning the growth species and mechanism in CVD diamond processes.