Infrared illuminated CdZnTe detectors with improved performance

It was found that IR illumination of a properly chosen wavelength and intensity can significantly improve spectrometric characteristics of CdZnTe quasi-hemispherical detectors [1]. Improving of the spectrometric characteristics is due to improvement of uniformity of charge collection by the detector volume. For operation at room temperature the optimal wavelength of IR illumination is about 940 nm, but for operation at lower temperature of -20 °C the optimal wavelengths of IR illumination is about 1050 nm. Infrared illumination can be performed using conventional low-power IR LEDs. Application of SMD LEDs allows produce miniature detection probes with IR illuminated CdZnTe detectors. We have fabricated and tested a variety of detection probes with CdZnTe quasi-hemispherical detectors from the smallest with volumes of 1-5 mm³ to larger with volumes of 1.5 cm³ and 4.0 cm³. The use of IR illumination significantly improves spectrometric characteristics of the probes operating at room temperature, especially probes with detectors of large volumes. The probe with the detector of 4 cm³ without IR illumination had energy resolution of 24.2 keV at 662 keV and of 12.5 keV with IR illumination.