Trapping induced Neff and electrical field transformation at different temperatures in neutron irradiated high resistivity silicon detectors

The trapping of both non-equilibrium electrons and holes by neutron induced deep levels in high resistivity silicon planar detectors have been observed. In the experiments transient current and charge techniques, with short laser light pulse excitation, have been applied in the temperature range of 77–300 K. Light pulse illumination of the front (p+) and back (n+) contacts of the detectors showed effective trapping and detrapping for electrons and holes. At temperatures lower than 200 K, the detrapping becomes inefficient, and the additional charge of trapped non-equilibrium carriers in the space charge region (SCR) of the detectors leads to dramatic transformations of the effective space charge concentration Neff and electric field. The current and charge pulses transformation data can be explained in terms of extraction of electric field to the contact opposite to the illuminated one.