Development of semi-insulating GaAs detectors for digital radiography

In this paper we present the results of an experimental study concerning different contact deposition processes on Semi-Insulating (S.I.) GaAs detectors aiming to study and optimize their performance in terms of leakage current, break-down voltage, charge collection efficiency and energy resolution when irradiated with 60 KeV photons; in particular the effect of the mesa etching treatment on the Schottky barrier side of the detectors has been studied. Such treatment certainly improves the detector performances related to the very important issue of the electric field uniformity. Detectors with satisfactory features in view of their possible application to Digital Radiography have been obtained.