Increased radiation hardness of detector-grade Cd0.96Zn0.04Te crystals by doping with In and Ge

Abstract

The resistibility (hardness) of the Cd0.95Zn0.05Te crystalline lattice against electron and γ-radiation was increased by doping with Ge and In atoms due to closeness of their ion radiuses to Cd. The doping was carried out with the aim to compensate the native and radiation-induced vacancy type defects such as Cd vacancies. The modification of defect-impurity state of initial (undoped), doped and irradiated samples was investigated by using non-destructive methods of low-temperature photoluminescence (LTPL) and Raman scattering. The material quality of studied Cd0.95Zn0.05Te crystals was evaluated by the experimentally obtained Huang-Rhys factor, the ratio Iex/Idef of intensities of exciton and defect-related bands in the PL spectra and the corresponding 2LO/1LO ratio from the Raman spectra. The optimal concentrations of In and Ge dopants in the solid phase were determined. The mechanisms of modification of defect-impurity states in irradiated and doped crystals as well as the interaction between the initial (native), doping-induced and radiation-induced defects were discussed.