In hydrogenated high-purity Si, the vacancy-oxygen $\left(V\mathrm{O}\right)$ center is shown to anneal already at temperatures below $200°\mathrm{C}$ and is replaced by a center, identified as a vacancy-oxygen-hydrogen complex, with an energy level $0.37\mathrm{eV}$ below the conduction-band edge and a rather low thermal stability. At long annealing times, the process is reversed and the concentration of the latter defect is reduced, while the $V\mathrm{O}$ center partly recovers. The divacancy $\left(V_2\right)$ center anneals in parallel with the initial annealing of the $V\mathrm{O}$ center, and the loss in $V_2$ exhibits a one-to-one proportionality with the appearance of a hole trap $0.23\mathrm{eV}$ above the valence-band edge attributed to a divacancy-hydrogen $\left(V_2\mathrm{H}\right)$ center.

• Received 5 September 2007

DOI:https://doi.org/10.1103/PhysRevB.77.073206