Temperature-Dependent Measurements of Time-of-Flight Current Waveforms in Schottky CdTe Detectors

Temporal evolution of the time-of-flight current waveforms of Schottky CdTe detectors as a function of the DC bias duration has been measured at several different temperatures from 278 K to 315 K to investigate the nature of the defects responsible for the polarization phenomena. The electron transient current waveforms under the application of DC bias show polarization as evidenced by a change in the waveforms continuously from having a plateau to having a peak at the trailing edge and by the shift of the peak position to later times with an increasing DC bias duration. Three relaxation processes with time constants from less than a second to as long as hundreds of seconds at room temperature are involved in the evolution. On the basis of the observed temperature dependence of the internal electric field evolution, we have concluded that two out of three relaxation processes are attributed to the ionization of defects at 0.54 eV and 0.6 eV.