Carrier transportation and polarization properties in CdTe diode detectors

The carrier transportation properties of a P-intrinsic-N (PiN) type CdTe diode detector for radiation spectrography was evaluated under the non-polarized and polarized condition with high speed signal processing method for a practical photon-counting system. The rise-up time distribution in each energy region was obtained by our system in each operation condition. These results suggest that the polarization affects transportation speed of holes slower than electrons, because the rise-up time distribution in same detection efficiency of the polarization condition (passage of time 90 min at bias voltage 200 V), and the non-polarization condition with lower bias voltage (passage of time 1 min at bias voltage 50 V) shows obviously different tendency by energy region. We believe our new approach could give key information for analyzing the polarization phenomenon in CdTe diode detectors.