Migration of interstitials in silicon

Abstract

We calculate total configurational energies for interstitial aluminum and silicon in silicon. The calculations, based on the self-consistent Green's-function technique, are done for a selective migration path along the "empty" channel in crystalline silicon. Short- and long-range structural distortions are found to be sizable and strongly varying along the migration path. Carrier capture is possible along the migration path, resulting in a drastic dependence of the migration barrier on the nominal charge-state of the defect. For aluminum migration in p-type silicon we find a barrier of VB=(1.30.5) eV, which in n-type material can be lowered by VB=(0.80.4) eV due to carrier capture. Both numbers agree well with experiment. Assuming a similar migration path for interstitial silicon the calculated values are VB(0.40.5) and (2.00.4) eV. In addition, the heat of tetrahedral formation of interstitial Si is evaluated to be HI 4.7 eV. © 1984 The American Physical Society.