Influence of character of heat removal from a crystal on the shape of its lateral surface in growth of bismuth germanate by the Czochralski method

The authors have investigated how the shape of the side surface of a crystal is influenced by the temperature distribution in the growth furnace and the melt before crystallization and also the variation in the temperature gradient above the melt in the process of growth of a crystal of constant cross section with fixed rates of pulling and rotation. They show that the face development of the crystal is due to the decrease in heat emission from the crystal and of the radial temperature gradient in the melt. They establish a relation between the shape of the side surface of the crystal and the shape of the crystallization front. Face development of the side surface of the crystal arises with change of the shape of the crystallization front from convex toward the melt to plane