Simulation of the kinetics of oxygen complexes in crystalline silicon

The formation kinetics of thermal double donors (TDD's) is studied by a general kinetic model with parameters based on accurate ab initio total-energy calculations. The kinetic model includes all relevant association, dissociation, and restructuring processes. The simulated kinetics agrees qualitatively and in most cases quantitatively with the experimentally found consecutive kinetics of TDD's. It also supports our earlier assignments of the ring-type oxygen chains to TDD's [Pesola et al., Phys. Rev. Lett. 84, 5343 (2000)]. We demonstrate with the kinetic model that the most common assumption that only the O₂ dimer acts as a fast diffusing species would lead to an unrealistic steady increase of the concentration of O₃. The neglect of restructuring processes leads to an anomalous increase of oxygen dimers and negligible concentrations of TDD's. The capture of interstitial oxygens by diffusing oxygen chains and the escaping of interstitial oxygens from the chains fully dominate the formation kinetics.