Step Patterns on {100} Faces of Diamond Crystals As-Grown in Mg-Based Systems

Abstract

In this article, we report the unusual growth of diamond crystals produced in Mg–C and Mg–Ge–C systems at high-pressure, high-temperature conditions. We have found that the growth of the habit {100} faces occurs by deposition of a substance (carbon) on two nonequivalent {100} and {111} surfaces. Precipitation of carbon atoms on the (100) plane occurs by elementary layers with a thickness of about 0.1 and 0.2 nm. The change in the density of elementary steps leads to the formation of step bunches that transform into faceted macrostates with an increase in their thickness of more than 400 nm. The maximum inclination angle of macrostep ends corresponds to the {111} faces position. As a result, singular stable {111} microfacets are formed at the ends of the macrosteps, which themselves grow layer by layer. The deposition of carbon on {100} and {111} surfaces of one simple form of diamond crystals leads to the zonal structure of {100} growth sectors.

Faceted-rough surface with disassembling of macrosteps in nucleation-limited crystal growth

“…As pointed out by Alexander et al 10 , 2D nucleation at the “valley” of the hillock, which is a concave line on the surface and corresponds to the lower edge of a faceted macrostep, has a lower activation energy than 2D nucleation on the {010} terrace surface. A similar 2D nucleation from the lower edge of a macrostep is observed experimentally for diamond 68 . These observed 2D nucleations at the lower edge of a macrostep are consistent with the present Monte Carlo results for a faceted-rough surface.…”

Mineral Growth beyond the Limits of Impurity Poisoning

“…Our data on the growth of vicinal surfaces close to kinetic arrest match the earlier experimental observations for potassium dihydrogen phosphate crystals poisoned by Fe 3+ , , and the more recent observations for diamond crystals as-grown in Mg-based systems . The kinetic differences between surfaces populated solely with elementary steps or with macrosteps are striking.…”

Relationship between Macrostep Height and Surface Velocity for a Reaction-Limited Crystal Growth Process

“…If Δμ > 0, then the crystal grows and nucleation occurs at the lower edge of the macrostep while growth occurs on both the (001) and (111) surfaces (Figure a). This 2D nucleation and growth at the lower edge of the faceted (111) side surface of a macrostep was observed in the case of diamond crystal in Mg-based systems . Conversely, if Δμ < 0, then the crystal evaporates or dissolves.…”

“…Although self-organized faceted macrosteps are known to lower the quality of crystalline SiC, dislocations penetrating the crystal have been shown to end at the side surfaces of macrosteps. − Hence, the intentional introduction of macrosteps can effectively decrease the dislocation density in a SiC crystal. In addition, controlling the self-assembly and disassembly of faceted macrosteps is an important aspect of fabricating semiconductor crystals. , …”