The dissociative diffusion mechanism with charge effects I: One-dimensional in-diffusion

in this paper we formulate a model of the dissociative mechanism for solid-state diffusion, which we analyse using asymptotic and numerical methods. The substitutional impurity is fixed to be singly negatively charged, while the interstitial impurity can have any charge and the vacancies any non-negative charge. The one-dimensional in-diffusion problem is considered and the impurity diffusion is shown to be very sensitive to the charge states of the interstitial impurities and vacancy defects. Some of the results are of broader interest with regard to the properties of systems of nonlinear diffusion equations, notably in terms of phenomena relating to a finite speed of propagation.