Properties of p+-n structures with a buried layer of radiation-induced defects

The p+-n structures based on n-type Si with dopant density 1.7x1013-1.2x1014 cm-3 were irradiated with 238Pu α particles. A layer containing radiation-induced defects with a density of the order of 3x1013 cm-3 was produced at a depth of 20 μm. This defect density gave rise to intense draining of nonequilibrium carriers in the injection-extraction regime with stationary injection as well as with pulsed generation by single particles. This makes it possible to treat the damaged layer as a plane, introduced into the bulk, with an infinite surface recombination rate. The radiation-induced defects also participated in decreasing the conductivity. A characteristic space charge distribution and, correspondingly, a bias dependence of the capacitance are observed in the structure under reverse bias. Despite the presence of formally three charge regions, four sections appear on the capacitance curve. This latter effect is due to the 'additional' charge step arising in the contact potential difference field and is characteristic of compensated deep levels in semiconductors