1. Nonproliferation and National Security Seminar

    "Dislocation dynamics and engineering of (Cd,Zn)Te"

    Presented by Prof. Peter Rudolph, Crystal Technology Consulting (CTC), Germany

    Wednesday, June 19, 2013, 10 am
    Building 197D, NNDC Conference Room

    The dislocation substructuring of (Cd,Zn)Te is treated. Cellular patterns are responsible for charge transport inhomogeneities in radiation detectors. Their genesis relates to i) dynamic polygonization in the course of plastic relaxation due to thermomechanical stress, ii) high-temperature dislocation dynamics combining glide with point-defect assisted claim, and iii) morphological instability of the propagating crystallization front in the form of cellular interface shapes. All three reasons will be discussed in detail. Cells are also observed in low-temperature THM Cd1-xZnxTe crystals, probably, correlating with morphological interface instability. An effective melt mixing is required. A newer concept of acoustic waves (avalanches) emission due to micro obstacles (precipitates, vacancy condensations) is presented. Substructures should be damped by adherence to the lowest possible thermomechanical stress during growth, solution hardening and near stoichiometric growth conditions.