Gap States Caused by Oxygen Precipitates and Their Hydrogen Passivation in Czochralski Silicon Crystals

Abstract

In order to investigate the gap states caused by the oxygen precipitation, we performed deep level transient spectroscopy measurements on silicon crystals containing various types of oxygen precipitates. For all types of the oxygen precipitates, a new signal in the gap-state density was observed at about Ec — 0.25 eV, as well as the previously reported peak at about Ev + 0.3 eV. Both peaks were attributed to the defect due to oxygen precipitation. This distribution of the gap-state density is very similar to that of the well-known Pb center originating from the dangling bond of a silicon atom at the interface between the silicon and silicon dioxide. These gap states were further found to be passivated by hydrogen, similarly to the case of the Pb center.