GaAs X-ray coordinate detectors

GaAs coordinate detectors for X-ray systems of scanning type have been deve loped. Two modifications of the detectors have been constructed for ionizin g radiation detection in parallel and perpendicular to the electric field d irection in the detector bulk. The detectors have 64 active regions with 10 0 mum pitch. In order to reach the minimum value of coupling capacitance an d resistance coupling between active regions, the latter is separated by na rrow gaps on unit cells. The gaps are made by means of reactive ion etching . The detectors are fabricated on the base of vapor-phase epitaxial materia l 40-45 mum in thickness with free carriers concentration of p(0) = 10(12) cm(-3). Input capacitance of a detector cell is 0.25 pF, dark current is 30 -50 pA per cell. The detectors have almost 100% charge collection efficienc y for all types of ionizing radiation. High resolution of the detector allo ws to detect structures of a spectrum from the Am-241 source in the energy range of 14-17 keV. (C) 2001 Published by Elsevier Science B.V.