THE GROWTH AND COMPARISON OF LARGE-DIAMETER VERTICAL BRIDGMAN CDZNTE AND CDTE

There is currently a need for high yields of large-area CdTe and Cd1-x ZnxTe substrates for the growth of infrared (IR) detector material. We have recently grown high-quality, 64 mm diameter, vertical Bridgman C d1-xZnxTe (x = 0.04) and CdTe under virtually identical conditions, wi th an axial thermal gradient of 5-degrees-C cm-1 at the ampoule wall, a solidification velocity of 1.0 mm h-1, and a post-solidification coo ling rate of 10-degrees-C h-1. The growth program was designed to mini mize excess stress in the crystals. We have obtained large-area (111)- oriented wafers from each boule. We explore the defect structure of th ese wafers using X-ray rocking curve (XRC) mapping, whole-wafer X-ray synchrotron white beam topography, chemical etch pit analysis, and opt ical and infrared microscopy. We also utilize Fourier transform infrar ed (FTIR) transmission mapping to explore the chemical and the optical properties of the materials. We have correlated the structural, chemi cal, and optical properties with the effects of substituting Zn into C dTe and the corresponding physical and mechanical properties of the te rnary CdZnTe. In particular, CdZnTe exhibits a decrease in crystalline defects and an improvement in morphological uniformity, increasing it s suitability for use as IR detector substrate material.