Reduction of Micro-Cracks in Large Diameter InxGa1-XSb Bulk Crystals

The ternary alloy, In{sub x}Ga{sub 1-x}Sb, is a compound semiconductor of tunable bandgap in the range of 0.18-0.72 eV, making it useful for infrared range optoelectronic devices. Utilizing a unique system based upon vertical Bridgman technique, large diameter (50 millimeter) In{sub x}Ga{sub 1-x}Sb polycrystals of composition ranging in x from 0.015 to 0.988 were grown. Methods of mixing the melt during solidification, including the accelerated crucible rotation technique (ACRT), have been used in conjunction with optimization of the furnace temperature gradient profile to significantly reduce micro-cracking in the crystal boules while accelerating the growth rate from less than a millimeter per hour to three millimeters per hour. In this paper, the experimental system and crystal growth parameters for a set of ternary experiments will be detailed. Scanning probe microscopy (SEM) images of vertical cross-sections of In{sub 0.15}Ga{sub 0.85}Sb samples show a 95.8 percent reduction in micro-cracking resulting from specific melt mixing schemes. The mechanism for micro-crack removal during bulk alloy growth will be discussed briefly