Physical Review B
The diffusion equation is solved for a semi-infinite region in the case of irradiation-enhanced diffusion produced by a diffusion coefficient falling off exponentially in the medium. Near the surface the concentration profile due to enhanced diffusion has a larger concentration than the profile due to thermal diffusion; conversely far from the surface the enhanced-diffusion profile has a lower concentration than that due to thermal diffusion. Thus, this type of enhanced diffusion results in a more abruptly changing profile than does thermal diffusion.
J. Kowall, D. Peak, and J.W. Corbett "Impurity-Concentration Profile for an Exponentially Decaying Diffusion Coefficient in Irradiation Enhanced diffusion," Physical Review B 13, 477-478 (1976). DOI: 10.1103/PhysRevB.13.477