The mechanism of radiation-enhanced diffusion of oxygen in silicon at room temperature

Undoped and tin-doped samples of silicon containing oxygen have been irradiated with 2 MeV electrons at room temperature and subsequently annealed. It is verified that (Sn-V) complexes dissociate at a temperature of about 160 degrees C. A comparative study was made of the rates of removal of stress-induced dichroism of the 9 mu m infrared absorption band due to oxygen in the two types of material as a result of similar electron irradiation. The rate in the tin-doped material is lower than that in undoped material by a factor of six, and there is a corresponding reduction in the generation rate of (O-V) complexes. Irradiation of similar samples held at 200 degrees C produced the same results for undoped material but the rate in tin-doped samples was then almost as high as in the former samples. It is deduced that (O-V) complexes capture silicon self-interstitials to regenerate isolated oxygen interstitial impurities and that the dichroism is lost in the overall process of complex formation and destruction.