New model for dopant redistribution at interfaces

Abstract

A new model for dopant redistribution at an interface is derived and verified by data from segregation and outdiffusion experiments. In the present model, a third phase, the interface layer itself (interphase), is considered in addition to the adjacent bulk phases for the first time. The dynamics of the three-phase system is described in terms of rate equations. In case that all three phases are identical, i.e., constitute one single homogeneous phase, this model effectively reduces to an ordinary diffusion equation for a bulk phase. The immediate advantage of this formulation is that the coupling between the redistribution at the interface and the diffusion in adjacent bulk phases can be described in an unambiguous and consistent way derived from first principles. In the limit of equilibrium segregation, the interface dynamics and bulk diffusion decouple, and the model reduces to diffusion equations in bulk phases supplied with Dirichlet boundary conditions at the interface given by analytic solutions of the equilibrium interface dynamics.