GROWTH OF GALLIUM ANTIMONIDE BY VERTICAL BRIDGMAN TECHNIQUE WITH PLANAR CRYSTAL-MELT INTERFACE

High quality single crystals of GaSb were grown using vertical Bridgman technique with a planar melt-solid interface. Various factors affecting the interface shape during growth were investigated. In general, the shape of the freezing isotherm was found to depend on the furnace temperature profile near the melt-solid interface, the ampoule lowering rate, the ampoule geometry, the mode of heat extraction from the tip of the ampoule and the extent of lateral heat loss from the side walls of the ampoule. A critical ratio of temperature gradient of the furnace at the melting point to ampoule lowering rate was found to be necessary for planar interface shape during the growth. The sensitivity of the interface shape was found to decrease with increasing temperature gradient of the furnace and ampoule diameter. Crystals grown by employing the flat melt-solid interface exhibited superior quality than those with non-planar interfaces.