A reversible transformation between the (2 x 2) surface reconstruction, and the unreconstructed (1 x 1) surface of the hexagonal phase, was studied during growth via molecular beam epitaxy. The transition was considered to occur at a particular surface stoichiometry which depended upon the net arrival rate of reacting species at the growth surface. The (2 x 2) surface reconstruction, as observed by using reflection high-energy electron diffraction, was stable under a N environment. The half-order reconstruction disappeared during Ga-rich growth and yielded a (1 x 1) reflection high-energy electron diffraction pattern, plus the eventual accumulation of metallic Ga at the growth surface.

P.Hacke, G.Feuillet, H.Okumura, S.Yoshida: Journal of Crystal Growth, 1997, 175-176, 94-9