Simulation Studies of CdTe Pixel Detectors

We have performed simulation studies of CdTe pixel detectors using the commercial SDEVICE simulator by SYNOPSYS. We have incorporated energy levels and concentrations of defects in the band gap using the information by published compensation models. We have performed I-V simulation experiments. We simulated the transient behavior of the detectors due to the bombardment with alpha particles and X-ray photons. The simulation of the interaction with alpha particles required the description of the dependency on energy of the Bragg peak in CdTe, which we included in the material database file of CdTe. We investigated the relation of the charge collected at neighbor pixels with the depth of interaction of X ray quanta. The study has the following purposes: (a) To provide realistic current waveforms as input to electronics simulations needed for the development of pixel readout electronics. (b) To evaluate methods for the extraction of the depth of interaction. (c) To incorporate to this device simulator as much detailed information as possible about the material, about the electrodes and about the defects that degrade its performance and explore through numerical simulation their effect on charge collection.