THE EFFECT OF TEMPERATURE-GRADIENT AND AMPOULE VELOCITY ON THE COMPOSITION AND OTHER PROPERTIES OF BRIDGMAN-GROWN INDIUM-ANTIMONIDE

A systematic study of the role of the melt-solid interface position in determining the crystal quality of Bridgman-grown indium antimonide I ngots is made. The crystals are grown under various conditions of impo sed gradients and velocities. The gradient-to-velocity ratio Lambda in the crystal is seen to move the interface position above or below the melting-point isotherm and this in turn affects crystal quality and g rain structure. Post-growth investigations reveal that the growth take s place under off-stoichiometric conditions, for large as well as for small values of Lambda, undesirable for growth of high-quality homogen eous ingots of InSb. However, crystals grown under 'near-equilibrium' conditions are stoichiometric, show low defect density, improved grain structure and comparatively narrow rocking-curve width, with very hig h mobility. (C) 1998 Elsevier Science B.V. All rights reserved.