Optical Characterization of Magnesium Doped Indium Antimonide Bulk Crystal Using VDS Technique

Vertical directional solidification (VDS) technique is used to produce quality semiconductor crystals such as InSb and GaSb. Using this technique, magnesium doped Indium antimonide bulk crystal is grown. The Stoichiometric solution of Indium, Antimony and Magnesium were sealed in a quartz ampoule. The growth is carried out at 5mm/hour in an inert atmosphere and reduced pressure. During crystal growth, the temperature at the center of the furnace was held at 550 0 C and ampoule was lowered below melting point. The resultant ingot was found detached from the ampoule wall. The metallic smooth appearance of the crystal, uniform diameter across the length and other studies confirms the superior quality of the crystal. The crystal was cut in 2mm wafers and polished to mirror finish before characterization. The powder X -ray diffraction pattern shows a single peak dominating over other peaks of small intensity which indicate preferential orientation of the crystal. The absorption measurementswere carried out using FTIR.The absorption edge was shifted from 0.16eV to 0.156 eV.Hence the material is suitable for band gap modification of InSb.The tilt angle of the absorption edge is smaller than 90 0 which indicate presence of large number of charge carriers.