Preliminary results on Bridgman grown CdZnTe detector crystals assisted by ampoule rotation

Different rotation profiles were applied to the ampoule during Vertical Bridgman (VB) growth of Cd0.9Zn0.1Te (CZT) for enhancing compositional homogeneity, minimizing radial and axial segregation and stabilizing growth interface. The radial Zinc (Zn) segregation was significantly minimized. Improvements in the axial Zn segregation were also noticeable. The modifications in interface shapes during the growth were prominent from the photoluminescence (PL) studies. Improved grain structure was observed with growths containing lower (0.5 wt. %) initial excess Te; however with higher amount of initial excess Te (7.5 wt. %) high resistivity ingots with improved carrier properties were grown consistently but with lower single crystal yield. With more intense rotations, resistivity values within the ingot varied by an order of magnitude showing non uniformity in distribution of dopants.