Investigation of radiation defects in n+–p–p+ planar silicon neutron detectors

Deep level transient spectroscopy (DLTS), C–V and I–V measurements were carried out on silicon n+–p–p+ neutron detectors using the reaction 6Li(n,α)3H. The samples were investigated before and after irradiation with nuclear power reactor neutrons with fluence 1.0×1014 n/cm2. DLTS spectra of detectors wrapped in a cadmium foil during irradiation showed the presence of three major deep levels, while in the detectors not protected by foil, 6 levels were present. C–V measurements showed considerable difference between the C–V curves of detectors worked under these two conditions. The peculiarities were explained by the presence of negatively charged defects in the space-charge region of the diodes, created by the α-particles and 3H produced from the converting reaction 6Li(n,α)3H.