In situ deep-level transient spectroscopy measurements have been carried out on p-type silicon following MeV He, Si, and Ge ion implantation at 85 K. Deep levels corresponding to intrinsic and impurity-related point defects are only detected after annealing at temperatures above 200 K. In addition to divacancies, interstitial carbon, and a carbon–oxygen complex, the formation of another defect, ... [Show full abstract] denoted as K2, has been observed during annealing at 200–230 K in epitaxial wafers, and at 200–300 K in Czochralski grown material. The energy level of the K2 defect is located 0.36 eV above the valence band, which is very close to a previously observed level of the carbon–oxygen pair. The relative concentration of this defect is ∼ 10 times higher in samples implanted with Ge than in those implanted with He. Due to its formation temperature, equal concentration in epitaxial and Czochralski grown wafers, and absence in n-type samples, the K2 trap has been tentatively identified as a vacancy-related complex which probably contains boron. © 1999 American Institute of Physics.