MORPHOLOGY, INTERGROWTHS, AND GROWTH MECHANISMS OF DIAMOND CRYSTALS AT DIFFERENT STAGES OF THEIR FORMATION FROM GASES

Abstract

Morphology and growth mechanisms of diamond crystals in polycrystalline films synthesized from hydrocarbon gas have been studied under an electron microscope using secondary electron images. It was found that at the earlier nonequilibrium stage diamond crystals form truncated tetragonal pyramids and penta-rayed intergrowths of such pyramids. The crystals grow by the ordinary mechanism with periodic formation of two-dimensional seeds. Depending on the conditions of further growth, the pyramidal crystals are gradually transformed into stationary cubic or cuboctahedral forms. Crystals grow at this stage by the spiral mechanism at the corners of mounded and interpenetrated crystals, at dislocation steps formed during crystal intergrowth, and at the growth analogue of the Frank-Read dislocation source. The smallest height of the growth step is about ∼80 Å at all sources of layer growth, i.e., crystals grow by clusters comparable in size to this height.