Spatial distribution of the X- and γ- rays induced energy deposition on semi-insulating GaAs:Cr based pixel radiation detector

Radiation detectors based on Cr compensated GaAs are characterized by high resistivity and good electron transport properties. These characteristics, its high atomic number and good radiation hardness, make GaAs:Cr a promising semiconductor detector within a wide photon energy range. The excellent imaging performance of these detectors for medical and other several applications are already reported in the literature. In this study, the spatial distributions of photon radiation energy deposition on a GaAs:Cr pixel detector with the real device dimensions (900 μm thick, pixels of 45x45 μm² and pitch of 55 μm) are presented. The charge carrier distribution profiles generated by the incident photons was additionally determined and discussed. Using the calculated weighting potential for the detector was possible to estimate the percent of charge carriers that shall contribute to the signal generated in the device electrodes. All the calculations were made for the typical photon energies of ²⁴¹Am and the energy corresponding to the K_α1 characteristic lines of Mo. The MCNPX code system and ARCHIMEDES program were used for mathematical modeling of radiation transport in matter and for semiconductor device simulations respectively. (Author)