Oscillatory Interface Instability During Czochralski Growth of Heavily Doped Germanium

Oscillatory interface instabil ity associated with constitutional supercooling was established uring growth of germanium single crystals from gall ium-doped melts by the Czochralski technique. The wavelength and phase velocity of the instabil ity were determined and found to be consistent with theory. The effects of pull ing and rotation rates on oscillatory instabil ity were quantita-tively correlated with the interface stability theory. It was shown that during rotational pull ing under conditions leading to constitutional supercooling, the destabilizing effects of rotation dominate its stabilizing effects for moderate rates of rotation in the presence of thermal asymmetry. During crystal pull ing from a doped melt, the region ahead of the growth interface may become constitu-tionally supercooled if the distribution coefficient of the solute differs from one. The original criterion for constitutional supercooling of Rutter and Chalmer