Deep-level transient spectroscopic measurements were made of both n-type and p-type crystals, which contained various types of O precipitate, in order to investigate the associated gap states. A new signal in the gap-state density was observed at about Ec-0.25eV, as well as a previously reported peak at about Ev+0.3eV. Both peaks were attributed to a defect that was generated by O precipitation. The observed distribution of the gap-state density was very similar to that of the Pb center which was due to the dangling bond of a Si atom at the interface between Si and SiO2 at the surface. The measured gap states could be passivated by H, as could the Pb center.

Gap states caused by oxygen precipitation in Czochralski silicon crystals M.Koizuka, H.Yamada-Kaneta: Journal of Applied Physics, 1998, 84[8], 4255-8