Investigation of the influence of light illumination on the characteristics of CdZnTe detectors

The spectral response of optical transmittance, spectrometry characteristics, output signal shapes and leakage currents of CdZnTe detectors with plane parallel electrodes under illumination with light within wavelength region of 400 - 1100 nm are presented. Illumination through the detector side without contacts was carried out at measurements. Significant change in the characteristics under irradiation with IR light with a wavelength close to the absorption edge of the CdZnTe was obtained. We can distinguish four characteristic regions of the spectrum. The first region from 1100 to 920 nm. In this region there is some improvement in charge collection efficiency, improving the energy resolution. Leading edge of output pulses (at registration of alpha particles) becomes practical linear. Leakage current remains unchanged. The second region from 920 to about 850 nm. In this region a significant deterioration in the charge collection efficiency and energy resolution were observed. The form of the leading edge of output pulses varies considerably, there were fast and slow components. Leakage current decreases by more than twice. The third area 850 to about 800 nm. In this area the charge collection efficiency and energy resolution improved up to theirs initial values. The form of the leading edge of output pulses changes up to the initial. Leakage current increases. The fourth area less than 800 nm. In this area, all characteristics remain practically unchanged. The measured spectral responses strongly depend on the intensity of illumination. We discuss the possible mechanisms to explain the effects associated with the change in the population of traps under the IR stimulation.