Reconstructions of GaN(0001) and (0001) surfaces: Ga-rich metallic structures

Abstract

Reconstructions of GaN(0001) and (0001̄) surfaces are studied by scanning tunneling microscopy and spectroscopy, by electron diffraction, by Auger electron spectroscopy, and using first-principles theory. Attention is focused on Ga-rich reconstructions for each surface, which are found to have a metallic character involving significant overlap between Ga valence electrons. The electron counting rule is thus violated for these surfaces, but they nonetheless form minimum energy structures.