Locally varying chemical potential and growth surface profile: A case study on solution grown Si(Ge)/Si

We investigate by transmission electron microscopy and atomic force microscopy the development of the growth surface profile of Si0.97Ge0.03/Si(001) grown from metallic solution near thermodynamic equilibrium. We show that sinusoidal surface undulations form to relax the mismatch strain elastically and result in a locally varying strain energy density at the growth surface. This leads to a locally varying difference in Gibbs free energy and thus to locally different growth rates. At sites where the strain energy is highest the layer dissolves. This dissolution in principle can be used to measure the local supersaturation of the solute at the growth surface.