Neutron-induced radiation damage in silicon detectors

Ion-implanted silicon pad detectors fabricated on different n-type and p-type silicon wafers with initial resistivities between 2.6 and 12.9 k Omega cm were irradiated with neutrons of approximately 1 MeV energy, up to a fluence of 5*10/sup 13/ n cm/sup -2/. The evolution of diode leakage current and capacitance characteristics is presented as a function of the neutron fluence. The reverse diode current increases proportionally to the neutron fluence. There is evidence that the doping of the initial n-type material evolves towards intrinsic and inverts to an apparent p-type at fluences between 1*10/sup 13/ and 3*10/sup 13/ n cm/sup -2/, depending on the initial silicon resistivity. There is also evidence that p-type material remains of the same conduction type with a slight increase of the acceptor doping with fluence. The signal shape and the charge collection efficiency for incident beta particles were measured.<
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