Kinetic Modeling of Dopant and Impurity Surface Segregation during Vapor Phase Growth: Multiple Mechanism Approach

We propose a new kinetic model for surface segregation during vapor phase growth that accounts for multiple segregation mechanisms, including mechanisms for terrace mediated exchange and step edge mediated exchange. The major result of the model is an analytic expression for the experimentally measured segregation length and profile broadening that can be readily calculated without the need for numerical simulations. We compare the model to experimental measurements for the temperature dependence of segregation of Sb in Si(001). The model is able to accurately describe both the anomalous segregation at low temperature and the transition between equilibrium and kinetically limited segregation at high temperature. An excellent agreement is obtained using realistic energies and pre-exponential factors for the kinetic rate constants. The model can be applied to other segregating systems in planar geometries, including metallic and III-V semiconducting thin films.