Crystal Growth from the Melt under Destabilizing Thermal Gradients

Abstract

Direct time correspondence between crystal growth behavior and the thermal characteristics of the melt under destabilizing radients was estab-lished by means of "time markers " which were introduced into the growing crystals and simultaneously registered on the continuous recording of the thermal behavior of the melt. Employing Te-doped InSb, it was found that as solidification progressed, the melt exhibited successively turbulent convection, oscillatory thermal instabilities, and, finally, thermal stability. During turbu-lent convection, the crystals underwent pronounced transient back-melting and the average microscopic growth rate was found to be independent of, and about 20 times greater than, the average macroscopic growth rate; this microscopic growth rate was controlled by the convection characteristics of the melt and the thermal gradients in the solid. With the onset of oscillatory thermal instabilities, back-melt ing became less pronounced and then ceased. In this region the average microscopic and macroscopic growth rates were