Diamond growth mechanisms

This discussion formulates what we understand about the diamond growth mechanism. The growth mechanism is related to surface processes that are difficult to describe on the atomic scale because of their complexity and the lack of adequate tools for in situ observation and measurements. In this case, modeling of the growth process is required to fill the gap in experimental data. We refer to the diamond growth process as an active surface CVD because of the importance of surface processes. This requires consideration of the following issues ... 

Figure 5.5. Electron micrographs of different types of diamond film grown on silicon. The white bar shows the scale in micrometres (p.m) (thousandths of a millimetre), (a) The initial stages of diamond growth on a nickel substrate, showing individual diamond crystallites nucleating in scratches and crevices created on the surface by mechanical abrasion, (b) a randomly oriented him,...

Electrodeposition on boron-doped diamond has pointed to progressive growth mechanism, as confirmed by chronoam-perometric transients and ex situ AFM images [ 312]. At lower concentrations, lead ions are deposited directly on the diamond substrate, while at higher concentrations, deposits overlap and further deposition occurs on lead. At higher temperatures, the size of the nuclei is bigger. 

Based on these analyses on the SiC coating, the growth mechanism of the SiC layer on diamond is considered as follows. In the early stage of the SiC formation on diamond, a very thin SiC layer is formed on the diamond surface according to reaction (10.2) between diamond and SiO(g). Once the SiC layer is formed, this reaction does not proceed due to the protective layer of SiC. The carbon sheet and felt in an alumina crucible act as the carbon source. The reaction of C02(g) with these carbon sources will produce further CO(g) and deposit SiC(s) by reaction (10.7). Thin j3-SiC whiskers are observed on the surface of the SiC-coated diamond, suggesting the vapor growth of SiC. 

An in situ characterization study of HFC VD deposition has suggested that three kinetic periods are involved in diamond deposition firstly, an incubation period, secondly, a limited diamond growth period and finally an unlimited diamond growth period. It has been shown that three mechanisms of particle formation are operational during diamond CVD. 

Methods and Mechanisms of Synthetic Diamond Growth, F. P. Bundy. H. M. Strong, and R. H. Wentoif, Jr. 

In conclusion, we have discussed the use of C clusters as diamond nucleation sites on Si substrates. This nucleation method substitutes the current practice of polishing surfaces with diamond grits. We have also demonstrated how C clusters can be used to selectively grow diamond on Si surfaces. In addition, our process provides a means of better understanding the mechanism of diamond nucleation. From our experiments, we can also speculate the reason why surface pretreatment is not necessary in the case of flame torch diamond deposition methods. We postulate that C clusters formed by the torch are helping to nucleate diamond on surfaces. The use of C clusters for diamond growth on other substrate materials, and the details of diamond nucleation will be reported elsewhere. 

These defects are generally detrimental to electronic, thermal and mechanical properties of diamond films, although in some cases they may be neutral or beneficial. The frequently occurring defects appear to be stacking faults (twinned clusters with many re-entrant surfaces/comers), which are deemed to play a major role in enhancing diamond growth rates.t ... 

K. E. Spear, and M. Frenklach, Mechanisms for CVD diamond growth, in Synthetic Diamond Emerging CVD Science and Technology, (K. E. Spear, and J. P. Dismukes, eds.), John Wiley Sons, Inc. (1994)... 

Thermochemistry and Mechanism of Chemical Vapor Deposition Diamond Growth... 

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