Characterization of compensation and trapping in CdTe and CdZnTe: Recent advances

Results on the properties of the known impurities, Ge, Sn, V and Bi, and the lattice imperfections, VCd and TeCd are summarized. We discuss their role in compensation, and in buffering the variations in shallow electronic levels in the grown ingot. We demonstrate that (∼2÷3 kT) variations of the Fermi energy increases carrier trapping to the deep levels. Trapping is manifest in a photoconductivity signal that can be studied by photoconductivity methods, thus allowing to monitor the spectroscopic-grade material before fabricating the detectors. Our approach could be important in preventing the after-glow effect and polarization. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)