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 degrees 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 similar to 10(6) times the value of interstitial oxygen at 400 degrees C, with an activation energy of similar to 1.3 eV and a preexponential factor of similar to 3 x 10(-4) cm(2) s(-1). The transformation from TDD1 to TDD2 is well described by a first-order reaction having an activation energy of similar to 2.5 eV, strongly indicating that the process involves motion of interstitial oxygen atoms (O-i). This conclusion is further supported by the deduced value for the preexponential factor, being very close to that for the jump frequency of O-i. [S0163-1829(98)04843-7].