Growth of monocrystals of germanium from an undercooled melt

Abstract

Dissipation of latent heat being the main rate-controlling factor in crystal growth from the melt, a novel technique has been developed for the rapid growth of monocrystals of germanium and other materials with the diamond or zincblende structure. By dipping a properly orientated seed crystal into an under-cooled melt and withdrawing it at the same rate as it grows, monocrystals of indefinite length can be obtained with various shapes which are under reasonable control; in particular, crystals can be grown in the form of thin lamellae, demonstrating in a striking fashion that even in an isotropic medium of cubic symmetry, crystal growth can take place by the deposition of individual layers orientated along the close-packed {111} planes. Further evidence for growth by layer formation is deduced from etch experiments. The surfaces of some of these crystals have a high degree of perfection. Crystal surfaces as grown, and also after having been etched, have been examined in detail under the optical, phase-contrast and electron microscopes, as well as with a fine-focus X-ray beam; certain growth features are discussed and a possible mechanism is suggested for dendritic growth.