MBE growth of cubic GaN on GaAs substrates

We review our recent results on plasma-assisted molecular beam epitaxy of cubic GaN films on GaAs(001). The crucial role of the nucleation stage for obtaining epitaxial growth is highlighted by reflection high-energy electron diffraction and transmission electron microscopy. For the subsequent growth, it is found that the surface stoichiometry determines the phase composition of the epilayers as determined by X-ray reciprocal space mapping, Raman and cathodoluminescence spectroscopy. For an in situ control of the surface stoichiometry, we develop a method based on the transitions of the surface reconstructions of cubic (001)GaN. Films grown under conditions optimized by this method are single-phase cubic and exhibit intense excitonic luminescence up to room temperature.