FURTHER EXPERIMENTAL TESTS OF THE DEEP-ACCEPTOR MODEL

Deep-acceptor states have been hypothesised to be responsible for the observed changes in effective doping concentration in bulk damaged sil icon detectors. A hypothesis for anti-annealing as due to the break-up of multi-vacancy defects, such as V-3, in the damage clusters has als o been proposed. This paper presents data from silicon photodiodes irr adiated in steps up to 200 Mrad with Co-60 photons. Type inversion but no anti-annealing was observed in these devices, based on capacitance and signal collection measurements. The data support both the deep-ac ceptor model and the anti-annealing hypothesis. The presence of a deep -acceptor was confirmed by illuminating the diode during C-V measureme nts.