Advances in the crystal growth of semiinsulating CdZnTe for radiation detector applications

The growth of large-volume semi-insulating CdZnTe single crystals with improved structural perfection has been demonstrated by the electro-dynamic gradient (EDG) technique and active control of the Cd partial pressure in the ampoule. The EDG technique nearly completely eliminates the uncontrolled radiative heat transport commonly encountered in traditional Bridgman systems where the charge and furnace move relative to each other. The control of the Cd partial pressure allowed the solidification and cool-down of the ingots close to the stoichiometric composition. As a result, the formation and incorporation of large size (⩾1 μm diameter) Te inclusions was avoided during crystallization and ingots with high structural perfection were achieved. CdZnTe crystals with 10⁹-10¹⁰ Ωcm electrical resistivity, good detector performance and electron mobility-lifetime product as high as μT_e=1.2×10^-3 cm²/V were obtained using the EDG technique