Convection in melts and crystal growth

Convection plays a significant role in determining the electronic properties of semiconductor crystals grown from the melt. Inhomogeneities (doping striations) in these crystals can be caused by unsteady natural convection. Therefore, the origins of unsteady natural convection, which means fluctuating temperatures in a fluid, are investigated in this paper. Several effects have been found at increasing Rayleigh numbers Ra which cause fluctuating temperatures. But it was also observed, that unsteady convection became again steady if Ra was increased to higher values. This effect, which is called relaminarization, is very interesting for crystal growth and is discussed in this paper.