Dopant diffusion control in silicon using germanium

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Abstract
Theory and experiment reveal that germanium, in large quantities and when integrated in the crystalline silicon environment, has a long range influence on electrically active dopant species. In regions having very high concentrations of substitutional germanium, calculations predict, and experiments confirm, sharp distinctions between the diffusion pattern exhibited by n-type dopants and the diffusion pattern produced by p-type dopants. n-type dopant diffusion, whether the species occupies a substitutional site or an interstitial position, is predicted and observed to be retarded through regions of very high concentrations of germanium. On the other hand, the dual behavior pattern for p-type dopants, predicted successfully, results in diminished diffusion of interstitial dopant but enhanced diffusion when the species occupies a substitutional site.