A method to study uniformity of electrophysical properties of high-resistance CdZnTe crystals

Uniformity of properties of a semiconductor material is one of the important conditions to achieve high spectrometric performance of ionizing radiation detectors. To study uniformity of electrophysical properties of crystals, an original method for acquisition of distributions of local values of a dielectric permittivity ε´ and tangent of a dielectric loss angle tanδ_M in high-resistance semiconductors is offered. The method was approved on Cd_1-xZn_xTe (x=0.1 to 0.16) crystals grown by Bridgman method under high pressure of inert gas. Locality and reproducibility of measurements are provided by a special design of a movable electrode, with both the area and the hold-down pressure of the electric contact being unvaried. Differences in ε´ and tanδ_M distributions over the sample´s area and an effect of uniform monochromatic illumination at a varied wavelength on these distributions are revealed. The physical nature of revealed irregularities is analyzed with involving results of researching CdZnTe crystals by diverse methods.