Carrier transport and trapping process in high-resistivity CdTe grown by a modified THM

Carrier trapping and detrapping processes in high-resistivity p-type crystals grown by a travelling heater method which is modified to provide a Cd reservoir (modified THM) have been investigated using a time-of-flight method. It is found that the trapping centers are located at about 0.05eV below the conduction band for electrons and at about 0.14eV above the valence band for holes, respectively. The carrier transport properties have been simply analyzed by assuming the presence of only one type trap level for electrons and holes, respectively. The influence of the Cd overpressure on carrier trapping and detrapping is discussed. The best values of the observed trapping time are 360ns for electrons and 1.0μs for holes in the crystals grown under Cd over-pressures of about 5x10-3atm