Kinetic study of oxygen dimer and thermal donor formation in silicon

Computer simulations of the generation kinetics of thermal double donors (TDD’s) in Czochralski-grown silicon have been performed and compared with experimental data for samples heat treated at temperatures between 350 and 420 °C for durations up to 500 h. The experimental data were obtained by Fourier-transform infrared spectroscopy exploring the recent finding that local vibrational modes can be associated with the individual TDD’s. A model assuming sequential generation of the TDD’s and a fast diffusing oxygen dimer has been found to quantitatively reproduce the experimental data. The diffusivity of the oxygen dimer was estimated to be $\sim {10}^6$ times the value of interstitial oxygen at 400 °C, with an activation energy of ∼1.3 eV and a preexponential factor of $\sim 3\times {10}^{-4}{\mathrm{cm}}^2{\mathrm{}\mathrm{s}}^{\mathrm{-}1}.$ The transformation from TDD1 to TDD2 is well described by a first-order reaction having an activation energy of ∼2.5 eV, strongly indicating that the process involves motion of interstitial oxygen atoms $\left({\mathrm{O}}_i\right).\mathrm{}$ This conclusion is further supported by the deduced value for the preexponential factor, being very close to that for the jump frequency of ${\mathrm{O}}_i.$