Solubility, diffusion and thermodynamic properties of silver in silicon

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Abstract
Concentration-depth profiles of Ag in Si have been measured with the aid of neutron activation analysis combined with serial removal of sections. The Ag diffusion appears to be very fast. In the bulk of dislocation-free Si wafers saturation is achieved after short periods of annealing. From this the authors conclude that interstitial Agi is the predominant configuration in Si without dislocations. Equilibrium concentrations of Agi are determined for temperatures between 1287 and 1598 K. The results are thermodynamically analysed, taking into account Ag-Si liquidus data. In dislocated Si much higher Ag concentrations are observed, which vary irregularly with the penetration depth. A comparison of the diffusion and solubility of Ag and Au in Si suggests that in Si with dislocations substitutional Ags may arise from Agi-Ags transitions. Finally an estimate of the Agi diffusivity is obtained.