Abstract
A detailed mechanism for heteroepitaxial diamond nucleation under ion bombardment in a microwave plasma enhanced chemical vapour deposition setup on the single crystal surface of iridium is presented. The novel mechanism of Ion Bombardment Induced Buried Lateral Growth (IBI-BLG) is based on the ion bombardment induced formation and lateral spread of epitaxial diamond within a ~1 nm thick carbon layer. Starting from one single primary nucleation event the buried epitaxial island can expand laterally over distances of several microns. During this epitaxial lateral growth typically thousands of isolated secondary nuclei are generated continuously. The unique process is so far only observed on iridium surfaces. It is shown that a diamond single crystal with a diameter of ~90 mm and a weight of 155 carat can be grown from such a carbon film which initially consisted of 2 · 1013 individual grains.
Highlights
A detailed mechanism for heteroepitaxial diamond nucleation under ion bombardment in a microwave plasma enhanced chemical vapour deposition setup on the single crystal surface of iridium is presented
The first is the appearance of bright areas in scanning electron microscopy (SEM) images taken by the in-lens (IL) detector which is sensitive to work function contrast
Depending on the specific bias enhanced nucleation (BEN) conditions, the patterns vary from compact homogeneous areas with smooth edges (Fig. 1(a)) to highly branched fractal-like structures (Fig. 1(c))
Summary
The present observation yields compelling arguments for the existence of a crystalline connection inside the carbon layer over the whole lateral distance at the end of the ion bombardment stage We interpret this finding as the decisive proof for the involvement of lateral diamond growth as the crucial process in the domain formation. At the transition to the domain area (i.e. the reaction zone “II”) the gradual drop in carbon coverage as derived from AES yields a further factor of 2 (in C-Impl/s) so that we end up with a value of 0.3–0.4 nm/C-Impl From these results, we first conclude that carbon implantation events (0.3–0.4 nm/C-Impl) are apparently by a factor of 6–8 more efficient in promoting phase transformation than the displacements considered in ref. The successful demonstration of heteroepitaxial diamond wafers is supposed to remove one crucial technological hurdle that existed so far for the realization of electronic devices and other high-end diamond applications
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