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

Abstract

Results on the properties of the known impurities, Ge, Sn, V and Bi, and the lattice imperfections, V Cd and Te Cd 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. Dedicated to Prof. Wolfgang Neumann on the occasion of his 65th birthday

Photoluminescence of CdZnTe thick films obtained by close-spaced vacuum sublimation

“…The PL band at 1.477 eV is due to Y center which corresponds to excitons bound on Te glide dislocations [49][50][51][52]. The nature of this band is supported by the results for CdTe crystal sample obtained from the bottom of the crystal bar where Y band strongly increases [50].…”

Post-growth Annealing of Cadmium Zinc Telluride Crystals for Room-Temperature Radiation Detectors

“…The compensation between the deep-level Te antisites, the Cd interstitials, and the Cd vacancies is considered responsible for the high resistivity of CZT. 6,7 This compensation could be lost due to extra Cd interstitials introduced during annealing in Cd vapor, thereby shifting the Fermi level toward the bottom of the conduction band or the top of the valence band. Furthermore, we measured the lowtemperature PL spectrum of as-grown and annealed CZT (Fig.…”

Composition dependence of structural and optical properties of Cd1−Zn Te thick films obtained by the close-spaced sublimation

“…In this case, the energy of LO-phonon is about 21 meV. According to [65][66][67][68] the PL band at 1.477 eV is due to Y center which corresponds to excitons bound on Te glide dislocations. Thus, the intensity of the Y band may be used as an indicator of the presence of dislocations in CdTe.…”