Self-diffusion of 31Si and 71Ge in relaxed Si0.20Ge0.80 layers
Self-diffusion of implanted 3 1 Si and 7 1 Ge in relaxed Si 0 . 2 0 Ge 0 . 8 0 layers has been studied in the temperature range 730-950 °C by means of a modified radiotracer technique. The temperature dependences of the diffusion coefficients were found to be Arrhenius-type with activation enthalpies of 3.6 eV and 3.5 eV and preexponential factors of 7.5 X 10 - 3 m 2 s - 1 and 8.1 × 10 - 3 m 2 s - 1 for 3 1 Si and 7 1 Ge, respectively. These results suggest that, as in Ge, in Si 0 . 2 0 Ge 0 . 8 0 both 3 1 Si and 7 1 Ge diffuse via a vacancy mechanism. Since in Si 0 . 2 0 Ge 0 . 8 0 7 1 Ge diffuses only slightly faster than 3 1 Si, in self-diffusion studies on Si-Ge 7 1 Ge radioisotopes may be used as substitutes for the "uncomfortably" short-lived 3 1 Si radiotracer atoms.