Electrical Properties and X-ray Sensitivity of Semi-insulating CdZnTe: Pb Crystals

High purity Pb-doped CdZnTe single crystals were grown by the vertical Bridgman method and their electrical properties and X-ray sensitivity were investigated. The doping concentration of Pb was about 1 times 1019 cm-3. The resistivity of Pb-doped CdZnTe single crystal was 2 times 109 Omega-cm and its values were three orders higher than that of non-doped CdZnTe single crystals. The temperature dependence of resistivity of these crystals was performed between 200 K and 300 K region. The plot of log(rho) versus 1000/T was represented by straight lines and its slopes had shown the 380 meV. In addition to, the type of conductivity of this crystal was derived from the position of Fermi level and its shift in band gap to the temperature. From the PL spectrum, we have confirmed that these phenomena are originated from the compensation process of Cd vacancies which are the most abundant acceptor in CdZnTe. Also, the effects of Pb-doping on the mobility was studied by TOF (time of flight) measurement. X-ray sensitivity in the 241Am measurement was not exactly indicated due to the leakage current.