Diffusion of beryllium in Ge and Si–Ge alloys.

Diffusion of implanted ⁷Be in Si_1-xGe_x (x=0.20,0.65,1.00) systems has been studied under intrinsic conditions in the temperature range of 460–720 °C by the modified radiotracer technique. Arrhenius-type behavior with activation enthalpies of 2.0 eV for Ge and 2.5 eV for the Si–Ge alloys was noted. Unexpectedly, the diffusivity of beryllium is higher in the Si_0.80Ge_0.20 material than in Si_0.35Ge_0.65 which is discussed in terms of possible prevailing diffusion mechanisms. It is proposed that Be diffusion in Si_1-xGe_x systems is dissociative mechanism dominated for germanium rich materials and the kick-out (or interstitialcy) mechanism dominates in silicon rich materials. [ABSTRACT FROM AUTHOR]