Electrical characterization of large volume CdZnTe coplanar detectors

The electrical behaviors of two large volume CZT coplanar detectors in the voltage and temperature application range are presented in this work. Two different regions are treated: bulk and anode surface. I-V curves were acquired at different temperatures in these two regions. Experimental results were analyzed by treating the device as a metal-semiconductor Schottky barrier. Two different formulations were used for modeling this structure: the interfacial-layer thermionic-diffusion model, considered as a complete and general theory, and the diffusion model as a more specific approach. It will be shown that the diffusion model is sufficient to reproduce the results obtained for biases and temperatures normally used in operation. A detailed description of this model is provided. In the anode face, the diffusion model is compared with the space-charge-limited current theory. Differences found in the two regions studied are outlined in this paper. Finally, the influence of the electrical parameters in the design of future detectors is discussed.