Charge collection in X-ray pixel detectors based on semi-insulating GaAs doped with Cr

An analysis of the performance of X-ray pixel detectors based on semi-insulating GaAs doped with Cr has been carried out. An analytic form for electron and hole currents has been obtained. The detector based on our material has high charge collection efficiency only when positive potential is applied to pixels, in contrast to semi-insulating materials (LEC SI-GaAs). A mean charge of a pixel contact is calculated for photon energy of 30 and 60 keV. The maximum mean charge is 3000e for the detector thickness of 300 μm and photon energy of 30 keV and 2300e for the detector thickness of 600–800 μm and photon energy of 60 keV.