Surface stress and interface formation

We discuss the role of surface stress during the initial stages of adsorption of As and Ge on Si(001). At submonolayer coverages the adsorbing species displaces Si atoms from the terraces, driven by a reduction of surface stress, leading to mixed terrace composition. As the coverage increases to one monolayer, chemical effects become dominant, leading to complete termination with Ge or As atoms. Depending on kinetic limitations, the surface at one-monolayer coverage may be smooth or rough. The reduction of surface stress by displacive adsorption provides a lower-energy pathway than growth by simple step flow and may play a role in the formation of a wide variety of (epitaxial) interfaces. © 1993 The American Physical Society.