Flux-dependent electric field changes in semi-insulating CdZnTe

We studied polarization in semi-insulating detector-grade cadmium zinc telluride without and with high optical flux. We employed the Pockels electro-optic effect combined with two perpendicular sources of light. A beam of red light or an infrared laser was applied parallel to the direction of the electric field acting as a source of electron-hole pairs. Infrared radiation from the monochromator illuminated the sample perpendicular to the direction of the electric field and changed the occupation of deep levels and therefore the depth profile of the bulk electric field. Spectral measurements of the Pockels effect were used to determine energy levels responsible for polarization and to find the optimal wavelength for optical depolarization of the detectors.