New vacancy-related defects inn-type silicon

Using deep-level transient capacitance spectroscopy, four dominant vacancy-related defects are found to be produced by room-temperature 2.5-MeV electron irradiation of n-type (p phosphorus concentration ∼${10}^{16}$ ${\mathrm{cm}}^{\mathrm{-}3}$) floating-zone silicon. This is in contradiction to the simple accepted model of vacancy trapping to produce predominantly oxygen- and phosphorus-vacancy pairs. We observe the oxygen-vacancy pair, but we now have two candidates for the phosphorus-vacancy pair. One of these displays properties suggestive of configurational metastability with four distinct configurations. We suggest that the remaining defect could be a vacancy-unknown impurity pair (carbon ?) or possibly the isolated lattice vacancy in a new, more stable configuration.