Stranski-Krastanow transition and epitaxial island growth

Abstract

A detailed examination is presented of the way in which the Stranski-Krastanow epitaxial islanding transition can be controlled by strain due to elemental segregation within the initially-formed flat ``wetting'' layer. Calculations using a segregation model are shown to accord well with experimentally measured critical wetting-layer thicknesses for the ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}/\mathrm{GaAs}$ system $(x=0.25--1).$ The strain energy associated with the segregated surface layer is determined for the complete range of deposited In concentrations using atomistic simulations. The segregation-mediated driving force for the Stranski-Krastanow transition is considered also to be important for all other epitaxial systems exhibiting the transition.