PROTON-INDUCED BULK DAMAGE EFFECTS IN GALLIUM-ARSENIDE DETECTORS

SI GaAs Schottky barrier detectors have been irradiated with high ener gy protons (24 GeV/c, fluence up to 1.20 x 10(14) p/cm(2)). The detect ors-have been characterized in terms of I-V curves and charge collecti on efficiency for incident alpha particles (Am-241) and by means of PI CTS, P-DLTS and TSC spectroscopic techniques. At the highest fluences a significant degradation of the electron and hole collection efficien cies has been observed, more evident in the hole collection, limited b y a hole trapping center with an activation energy of 0.56 eV. New ele ctron traps (0.15 eV and 0.20 eV) are observed only in the irradiated detectors. Furthermore, the concentration of the deepest (0.79 eV) ele ctron trap, the well known EL2, increases of one order of magnitude, t hus noticeably affecting the electron collection efficiency. For both the charge carriers, the collection efficiency is remarkably affected by the electric field, increasing with it.