Carrier transport properties of HPB CdZnTe and THM CdTe:Cl

Carrier drift mobilities of CdZnTe (CZT) grown by high-pressure Bridgman (HPB) method and chlorine doped CdTe grown by traveling heater method (THM) were measured by a time-of-flight (TOF) technique. A spectrometer grade crystal of HPB CZT shows room temperature electron mobility of 960 cm/sup 2//Vs and hole mobility of 56 cm/sup 2//Vs. Both electron and hole mobility of THM CdTe:Cl crystals are higher (1100 cm/sup 2//Vs for electrons and 88 cm/sup 2//Vs for holes) than that of the HPB CZT crystal. Both materials show a saturation of the electron mobility at low temperature around 100 K and a strong decrease of the hole mobility with lowering the temperature. A theoretical mobility calculation has been done by solving Boltzmann transport equation assuming several scattering mechanisms such as polar optical phonon, ionized impurity and alloy scattering. It is concluded from the comparison of the experimental and theoretical temperature dependence that shallow trap controlled mobilities are observed in both spectrometer grade CdZnTe and CdTe crystals.