Published in Phys. Rev. Lett. 79, 3934 (1997).

Reconstructions of the GaN(0001) Surface

A. R. Smith, R. M. Feenstra
Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
D. W. Greve
Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
J. Neugebauer
Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
J. E. Northrup
Xerox Palo Alto Research Center, 3333 Coyote Hill Road, Palo Alto, California 94304


Reconstructions of the GaN(0001) surface are studied for the first time. Using scanning tunneling microscopy and reflection high-energy electron diffraction, four primary structures are observed: 1×1, 3×3, 6×6, c(6×12). On the basis of first-principles calculations, the 1×1 structure is shown to consist of a Ga monolayer bonded to a N-terminated GaN bilayer. From a combination of experiment and theory, it is argued that the 3×3 structure is an adatom-on-adlayer structure with one additional Ga atom per 3×3 unit cell.

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