Schottky CdTe nuclear detectors are affected by bias-induced polarization phenomena when operating at room temperature. A space charge buildup occurs at the blocking contact causing the degradation in detection performance. By means of Pockels effect, we study the electric field distribution inside the detector and its variation with time and temperature. The analysis of the space charge has allowed us to point out the role of the Schottky contact and of carrier detrapping from deep levels in the polarization mechanism. Moreover, measured current transients have been quantitatively accounted for by the increase in the electric field at the blocking junction.

Diode-like In/CdTe/Pt detectors are widely used thanks to their excellent spectroscopic performance. However, when operated at room temperature they are not stable, and their performance degrades with time. The aim of this paper is to investigate in detail the physical mechanisms underlying this effect, by studying the evolution of the space charge inside the detector. Our approach makes use of the Pockels effect, by looking at the evolution of the electric field distribution inside the detector at different temperatures. The results show that a negative space charge accumulation occurs at the anode and that the process is thermally activated. The effect is attributed to a midgap acceptor which, under reverse bias, increases its ionization because of hole detrapping. Moreover, we compare the results with those obtained on stable detectors realized from nominally same crystals but having ldquostandard,rdquo i.e., not rectifying contacts. Consistently with the detection performance stability of this kind of detectors, the electric field is relatively stable. Furthermore, it decreases from cathode and it shows peculiar features which will be discussed in conjunction with charge transport properties.

Recently, diode-like In/CdTe/Pt detectors have been realized which look very promising thanks to their enhanced spectroscopic performance. Scope of this work is to investigate the electric field distribution inside these detectors and its temporal evolution by means of the Pockels effect. The implemented set-up allows us to map the electric field and thus to extract the field profiles between the contacts. The analysis shows that the field is mainly confined below the anode. After applying the bias, these detectors are not very stable at room temperature, and they present a pronounced degradation in spectroscopic performance. This degradation is correlated in this work to the evolution of the electric field which has been observed to dasiamovepsila towards the anode. We attribute this dasiapolarizationpsila behavior in CdTe detectors to the concomitance of two factors: the presence of deep levels in the bulk material, and the high hole barrier height of In on CdTe.