Bulk crystal growth process for compositionally homogeneous gallium indium antimonide substrates

The mode of redistributing the excess solute species at the melt-solid interface accumulated during the growth of bulk ternary semiconductor crystals is a key factor determining the spatial alloy composition and crystalline quality. Since the solidification temperatures vary with alloy composition, a control over both heat and mass transport during crystal growth is necessary for achieving spatial compositional homogeneity in the grown crystals. The goal of this work has to been to identify growth conditions necessary for compositionally homogeneous (within 1 mol% in the radial direction) substrates.; A comparative study of various melt stirring schemes with different axial temperature gradients and the resulting alloy distribution in the crystals has been presented in this thesis. A combination of axial thermal gradient of approximately 15°C/cm, accelerated crucible rotation (ACRT) with maximum crucible acceleration up to 100 rpm in 60 seconds and growth rate in the range of 0.2--0.5 mm/hr has been found to be most suitable for radially homogeneous Ga1-xInxSb crystals. Bulk polycrystals of 50 mm diameter Ga1-xInxSb across the entire composition range (x = 0--1) has been successfully grown under these conditions.; The below bandgap infrared transmission (up to 25 mum) in undoped Ga 1-xInxSb bulk crystals has been studied for the first time and found to be limited by native defects such as anti-sites and vacancies found in antimonide based III-V compounds. For the gallium rich alloy compositions (x < 0.5 in Ga1-xInxSb), the crystals exhibit p-type conductive behavior with increase in net acceptor concentration with increase in gallium content in the crystals. For x > 0.5 (the indium rich alloy compositions), the crystals exhibit n-type conductivity with increase in net donor concentration with increase in indium content in the crystals. (Abstract shortened by UMI.)...