Theory of the charged cluster formation in the low pressure synthesis of diamond: Part I. Charge-induced nucleation

Abstract

Based on several experimental observations, Hwang et al. recently proposed "the charged cluster model" [J. Cryst. Growth, 162, 55 -68 (1996)] to disentangle the "puzzling thermodynamic paradox" encountered in the gas-activated chemical vapor deposition (CVD) of diamond. Many unusual phenomena observed in the CVD diamond process can be successfully approached by the charged cluster model. However, there are a couple of important subjects still unsolved quantitatively. The first question is connected with the main driving force for this unusual nucleation in the gas phase. The second issue is related to the difference in the thermodynamic stability between graphite and diamond for a nanometer-sized cluster during the growth. In this study, we have theoretically examined the thermodynamic driving forces for the charge-induced nucleation, in general, and have applied this idea to the nucleation of the charged carbon-atom cluster. It was shown that the short-range ion-induced dipole interaction and the ion-solvation electrostatic effect (Born term) were mainly responsible for this unusual nucleation in the gas phase. The theoretical analysis presented in this article is quite generic and, thus, can be applied to any process that involves the charge-induced nucleation.

Nanocrystalline diamond film growth on plastic substrates at temperatures below100 °Cfrom low-temperature plasma

“…By developing this discussion, more elaborated investigations into the stability of nanometer-sized diamond have been made to date. [31][32][33][34][35][36] Badziag et al 31 have proceeded with the Nuth's discussion using a semiempirical quantum chem-istry calculations. They concluded that diamonds of 3-5 nm in size are more stable than graphite regardless pressure or kinetics.…”

“…Several other theoretical investigations have reached results of a similar peaked size distribution for diamond nanoparticles in a stable phase. [32][33][34]36 Raty and Galli, 34 in particular, have applied the discussion to the diamond CVD growth that requires the presence of hydrogen, using first-principles calculations. They found that the size distribution should exhibit a sharp peak at around 3 nm in the presence of hydrogen on the surfaces of diamond nanoparticles for a broad range of pressures and temperatures.…”

“…Hwang et al 35 have proposed a diamond CVD growth model by charged clusters. In elaborating the model theoretically, Jang and Hwang 36 have suggested remarkable reduction in the activation free energy for the diamond nucleation in the gas phase. They suggest that the diamond nucleation occurs in a plasma under certain conditions.…”

Diamond Nucleation and Seeding Techniques: Two Complementary Strategies for the Growth of Ultra-thin Diamond Films

“…These findings are supported by calculations, which predicted suitable plasma conditions. 17,18 A recent article has review the state-of-art of diamond homogenous nucleation models from bulk liquid. These calculations may explain why the homogeneous diamond nucleation is likely in carbon-rich stars and planets, such as Uranus and Neptune.…”

Diamond growth on faceted sapphire and the charged cluster model

“…However, the nucleation and growth mechanism of the CVD diamond remains inconclusive. Recently, the charged cluster model (CCM) [1][2][3][4][5] was proposed where the electric charges produced by gas activation are the nucleation sites for the supersaturated species. Charged nuclei are produced in the gas phase and the coarsening process of these nuclei eventually leads to the formation of charged clusters.…”