Silicon-induced nanostructure evolution of the GaAs(001) surface

By using scanning tunneling microscopy and reflection high-energy electron diffraction it is demonstrated that self-organized ordered Si structures develop during submonolayer Si deposition on vicinal GaAs(001) surfaces, provided the preferred adsorption sites in the trenches of the (2x4) reconstruction are filled with Ga. The evolution of different reconstructions with increasing Si coverages is accompanied by step bunching and de-bunching processes. This unexpected behavior is explained by the interaction between reconstructions and steps from a thermodynamic equilibrium view. For particular coverages the complex process leads to a separation of different surface phases and Si coverages on terraces and in step regions