Charge collection properties of GaAs detectors for digital radiography

In this paper we present the result of an experimental study concerning the charge collection efficiency (cce) properties of various (Semi Insulating) S.I.-GaAs detectors, when irradiated with 60 keV photons. Some of these detectors, 100 or 200 mu m thick, are equipped with a new type of Ohmic contact manufactured by Alenia S.p.A. (Italy), which allows the detector to withstand a bias voltage up to 700 V before break-down. A cce value of 100% has been measured for the 100 mu m thick detector. The behavior of a matrix of 36 square pixels, 200x200 mu m(2) spaced 200 mu m, has been investigated for the cross talk between adjacent pixels and for cce uniformity, obtaining good results. RI maestro, paolo/E-3280-201