Formation of carrier generation centers in pure Si upon interaction with fast ions

The radiation defects in p+-n-n+ structures based on pure n-type Si irradiated by α particles and fission fragments from natural-decay sources are studied by deep-level transient spectroscopy (DLTS). The nature of the components of the reverse current in the structures caused by carrier generation via deep levels is investigated. The systems of deep centers for light and heavy ions are found to be identical. A correlation between the generation component of the current and the concentration of the Eν+0.33 eV centers bound to interstitial carbon is observed after a low-temperature anneal. In the case of heavy ions the DLTS spectra do not have the expected peak positions and shapes associated with the pileup of local defects. An estimate of the generation rate in a model of local p-n junctions shows that clusters of defects create a significantly smaller current than does an equivalent number of defects with deep levels located in the n-type host of the structure