Nucleation and growth phenomena in chemically vapor-deposited diamond coatings

• Published in: Surface & coatings technology Vol. 36; no. 1; pp. 283 - 293
• Main Authors: Badzian, A.R., Badzian, T.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.1988
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/0257-8972(88)90158-2

The deposition of crystalline diamond coatings by microwave plasma-assisted chemical vapor deposition (CVD) is the main subject of this paper. The plasma is excited in a hydrogen-rich methane and hydrogen mixture with a substrate temperature of approximately 1000 °C. High chemical reactivity of the plasma limits the application of the CVD process to certain substrates. Autoepitaxy of diamond on diamond substrates has already been demonstrated, but nucleation of diamond on non-diamond substrates creates many conceptual and practical problems. Experimental observations of the nucleation of diamond on various substrates are presented and discussed. Several phenomena are connected with the growth mechanism of diamond: competition in nucleation between diamond and graphite, surface activity of the species, adsorption and desorption of hydrogen on the diamond surface and surface reconstruction. In turn, a collective interaction between the plasma, the growing surface and the bulk substrate is expected to be responsible for the observed maximum growth rate at approximately 1000 °C and the narrowing of the other process parameters. These delicately balanced interactions provide conditions for growing relatively perfect crystalline diamond films. The other issue is how to achieve a high growth rate of diamond. One approach is by a catalytic growth mechanism in which an intermediary role is played by some atoms such as boron, silicon, titanium and others. Growth of diamond films on titanium substrates may reach rates of up to 20 μm h -1.