Charge sharing on monolithic CdZnTe gamma-ray detectors: A simulation study

Monolithic CdZnTe gamma-ray detectors are used to build gamma cameras for nuclear medicine imaging but their energy resolution is currently limited by charge sharing between adjacent anodes. For this work, charge sharing is simulated using Ulysse, a numerical model that takes into account the physical processes of charge creation by ionizing radiation and charge transport within the semiconductor detector. The charge carrier cloud size, following the gamma-ray photon interaction, is computed by the Monte Carlo method. Electron cloud diffusion and charge induction on the electrodes are computed by the finite element method. This study shows that the electron diffusion strongly influences the final electron cloud diameter.