Dopant diffusion experiments in semiconductors yield the mobility of the element of interest and information about the possible mechanisms of atomic diffusion. In many cases the diffusion was described on the basis of Fick's law of diffusion, but this treatment was often too simple. Here, dopant diffusion in semiconductors was treated systematically on the basis of diffusion-reaction equations. Predictions on the shape of dopant-diffusion profiles that developed under specific experimental conditions were derived. It was illustrated that the charge states of the point defects involved in the diffusion process strongly affect the shape of the dopant profile under electronically extrinsic conditions. The relation between the shape of the dopant profile and the underlying mechanism of atomic diffusion, and between the apparent dopant diffusion coefficient and the point defect mediating the diffusion process was explained. With the advance in epitaxial deposition techniques and the availability of isotopically enriched elements, semiconductor isotope heterostructures could be grown, which were highly appropriate for studying the impact of dopant diffusion on self-diffusion. The modelling of the simultaneous diffusion of self- and dopant atoms in semiconductor isotope heterostructures was described and the advances resulting from this new diffusion approach compared to conventional diffusion studies that treat self- and dopant diffusion separately, were highlighted. The present results were intended to serve as a guide to understanding and accurately modelling the diffusion of dopants and their impact upon self-diffusion in semiconductors.

Self- and Foreign-Atom Diffusion in Semiconductor Isotope Heterostructures I - Continuum Theoretical Calculations. H.Bracht: Physical Review B, 2007, 75[3], 035210