On Polarization of Compensated Detectors

Abstract

This paper presents analyses of polarization effects in ohmic and junction sensors by detailed three-dimensional modeling. It is shown for the example of compensated ${{\rm Cd}_{1 - {\rm x}}}{{\rm Zn}_{\rm x}}{\rm Te}$ detectors that the compensating deep-levels can be also responsible for both bias-induced and ionization-induced polarization phenomena. The capture cross sections of the deep levels are shown to play a dominant role in the formation of the polarizing space charge. Calculations show that bias-induced polarization is not expected to occur in ohmic MSM structures as long as the mobility remains constant. Ionization-induced polarization is expected to occur equally in ohmic and Schottky devices, but the sign and the distribution of the polarizing space charge depend on deep level cross sections.