Surface roughening at the one-monolayer Sb/Si(100) interface

Using scanning tunneling microscopy observations, it has been found that the atomically flat 1-ML Sb/Si(100) interface is metastable at a temperature of about $750°\mathrm{C}$ and becomes rough upon brief annealing, although the Sb-dimer-row structure of the top layer is completely preserved. The roughening is explained by displacive adsorption of Sb (i.e., by substitution of the top-layer Si atoms by Sb atoms) and this phenomenon is suggested to be a common one for group-V adsorbates on Si(100) and Ge(100) surfaces.