The current transport mechanisms of n(+) -p silicon (Si) photo-detectors in different temperature and bias regions before and after irradiation with a dose of 350 kGy has been investigated and presented in this article. Temperature-dependent dark current-voltage (I-V) studies under forward and reverse bias were carried out for this purpose. In the temperature range studied, the dark current contribution in the low bias range is believed to be due to the generation-recombination of minority carriers in the space-charge region. Electron irradiation does not seem to have altered the dark current conduction mechanism. Capacitance-voltage (C-V) at various temperatures was measured to identify the presence of deep levels in the device. (c) 2007 Elsevier B.V. All rights reserved.