Surface and interface studies of GaN epitaxy on Si(111) via ZrB2 buffer layers

Gallium nitride films, epitaxially grown on Si(111) via a lattice-matched ZrB2 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 ZrB2(0001) clarify the origin of the N polarity.