Spectroscopic performance of semi-insulating GaAs detectors for digital radiography

We studied pixel radiation detectors for X-ray radiography based on semi-insulating GaAs: in particular, we investigated both annealed and non-annealed contact deposition techniques for the ohmic contact and both ring-guarded and non-guarded Schottky contact, in order to reduce the leakage current and to increase the maximum applied electric field. Spectroscopic characterization with a 60 keV 241 Am source has been performed. Among these different detectors, the CCE can reach 99 +/- 6%, while the energy resolution Delta E/E can go down to 4.1 +/- 0.2%.