Self-diffusion of 71Ge and 31Si in Si-Ge alloys

The tracer self-diffusion coefficients D-T of implanted Ge-71 and Si-31 in both relaxed monocrystalline SiyGe1-y epilayers and specimens made from bulk SiyGe1-y have been measured as functions of temperature T (653 degreesC less than or equal to T less than or equal to 1263 degreesC) and composition y (0 less than or equal to y less than or equal to 1) by means of radio-tracer techniques, in which serial sectioning was done by ion-beam sputtering. For all compositions, the T dependencies of D-T for Ge-71 and Si-31 are of Arrhenius type. They dependencies of the pre-exponential factors of the self-diffusion coefficients and of the diffusion enthalpies show. a break at y approximate to 0.65. This is interpreted in terms of a transition from interstitialcy-(y greater than or similar to 0.65) to vacancy-(y less than or similar to 0.65) mediated self-diffusion.