Monitoring surface stoichiometry with the (2x2) reconstruction during growth of hexagonal-phase GaN by molecular beam epitaxy

Reflection high-energy electron diffraction is used to study the stability of the (2X2) reconstruction on the (0001) surface of hexagonal-phase GaN as a function of growth parameters. The relationship between the critical conditions for existence of the reconstruction, which corresponds to a unique surface stoichiometry, is used to show the interdependency and scalability of growth parameters. A model is proposed to describe the stoichiometric balance of the species arriving on the surface at the critical conditions for observation of the reconstruction. Hall mobility of the GaN epitaxial layers was improved by growing under these conditions. (C) 1996 American Institute of Physics.