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As the Si counterpart of graphene, silicene may be defined as an at least partially sp2-hybridized, atom-thick honeycomb layer of Si that possesses π-electronic bands. Here we show that two-dimensional, epitaxial silicene forms through surface segregation on zirconium diboride thin films grown on Si wafers. A particular buckling of silicene induced by the epitaxial relationship with the diboride surface leads to a direct π-electronic band gap at the Γ point. These results demonstrate that the buckling and thus the electronic properties of silicene are modified by epitaxial strain.

Gallium nitride films, epitaxially grown on Si(111) via a lattice-matched ZrB(2) buffer layer by plasma-assisted molecular beam epitaxy, have been studied in situ by noncontact atomic force microscopy and also in real time by reflection high-energy electron diffraction. The grown films were determined to be always N-polar. First-principles theoretical calculations modeling the interface structure between GaN(0001) and ZrB(2)(0001) clarify the origin of the N polarity.

The structure and stability of the hydrogen-terminated (105) surface of Ge deposited on Si(105) substrates are investigated by scanning tunneling microscopy (STM). Investigations combining STM, electron energy loss spectroscopy, and theory reveal that Si incorporation into the surface Ge layer of hydrogen-terminated Ge/Si(105) drastically destabilizes the surface. The STM images obtained on this surface are well explained by the recently established rebonded-step structure model.