Spectral analysis of the photoconductivity for characterization of CdTe И CdZnTe detectors

Abstract

The results of the application of optical methods are considered: spectral analysis of photoconductivity in the range 400–1800 nm and field measurements of stationar photoconductivity to study the bulk and surface characteristics of CdTe and CdZnTe gamma-ray detectors. The studies of the photoresponse of the samples were carried out in different irradiation modes: modulated at a frequency of 25 Hz and a constant light flux. The measurements were carried out at room temperature on domestic and foreign materials of detector quality. Using the spectral photoconductivity method, the parameters of deep levels, which affect the detector properties, have been estimated in the studied materials. Based on the calculations of the field dependences of the photoconductivity, the volume and surface parameters of the capture and recombination of non-equilibrium carriers in the investigated detectors were determined. The results of calculating the transport characteristics of charge transfer by electrons μτe in detectors are compared with similar parameters measured using the traditional method of irradiating the detector with alpha particles. To measure the band gap in CdTe and CdZnTe at room temperature the method was modified for calculating ΔEg. The possibility of monitoring the Zn content in CdZnTe detectors using the spectral photoconductivity method is shown.