4.4.1 Conduction Model

  A dopant reaches an equilibrium state at the material interface when its chemical potential is the same on each side of the boundary. This redistribution may result in an abrupt change in the doping concentration across the material interface. The equilibrium ratio of the dopant concentrations on each side of the boundary is known as segregation coefficient m and is given by

 

The conduction model is the most simplest one. It pins the concentrations on both sides of the interface to a fixed relation (4.4-3), where k can be any function of the interface quantities or even a single value (k;SPMgt;0).

 

This model is used to convey the concentrations across the boundary without specifying any underlying exchange mechanism. By specifying k = m, the dopant segregation at the interface achieves thermal equilibrium.