The Space-Charge Region of Neutron-Irradiated Silicon p+n Junctions

A model has been developed describing the space-charge region of silicon p+n junctions in the presence of deep traps. These traps are assumed to be defects with discrete energy levels in the forbidden energy gap. This model is applied to high frequency (1 MHz) capacitance-voltage measurements of two neutron-irradiated silicon p+n junctions where Nd = 5 X 1014 cm-3 and 1015 cm-3. It was found that two acceptor traps at Ec-0.4 eV and Ec-0.58 eV adequately fit the data. Since the divacancy has similar levels, the divacancy is a logical defect to assign to these levels. In addition, it was found that the defect introduction rate was 0.95 cm-1 for one of the junctions (Nd = 5 X 1014 cm-3), fabricated in bulk material; whereas, for the other junction (Nd = 5 X 1014 cm-3), fabricated in epitaxial material, the defect introduction rate was 0.64 cm-1. These rates are consistent with those reported previously in the literature.