Layer-by-layer epitaxial growth of Mg on GaN(0001)

It is shown that Mg deposition at room temperature on a GaN(0001) surface, obtained in situ by molecular beam epitaxy, gives rise to a layer-by-layer epitaxial growth mode. The study by reflection high-energy electron diffraction and scanning tunneling microscopy clearly evidences that a two-dimensional nucleation growth mechanism occurs from the very first Mg monolayer deposited. A complete covering of the GaN surface is obtained from the deposition of the first two monolayers of Mg.