Optimization of a pixellated CdZnTe/CdTe detector for a multi-modality imaging system

The operation of any semiconductor detector depends on the charges movement created in the material after energy deposition. The charge in the bulk semiconductor induces image charges on the metal electrodes and therefore the charge movement towards the electrodes induces a current in the electrodes and external circuit. The details of how quickly and how far the bulk charge travels depend on the material parameters of mobility (mu) and lifetime (t), as well as the operating electric fields (E). The amount of image charge present at any instant of time (for a given amount of bulk charge) depends on the position of the bulk charge and the weighting potential of the electrode, which depends on the device structure and biasing. The design of the detector can therefore have a significant impact on its spectral performance.