Published in
MRS Internet J. Nitride Semicond. Res. 7, 3 (2002).
Review of Structure of Bare and Adsorbate-Covered GaN(0001) Surfaces
R. M. Feenstra (a), J. E. Northrup (b), and J. Neugebauer (c)
(a)Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213
(b)Palo Alto Research Center, 333 Coyote Hill Road, Palo Alto, CA 94304
(c)Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
Abstract
A review of surface structures of bare and adsorbate-covered GaN
(0001) and (0 0 0 -1) surfaces is presented, including results for In, Mg,
Si, and H adsorbates. Emphasis is given to direct determination of
surface structure employing experimental techniques such as scanning
tunneling microscopy, electron diffraction, and Auger electron
spectroscopy, and utilizing first principles computations of the total
energy of various structural models. Different surface stoichiometries
are studied experimentally by varying the surface preparation
conditions (e.g. Ga-rich compared to N-rich), and the stoichiometry is
included in the theory by performing calculations for various chemical
potentials of the constituent atoms. Based on the work reviewed here,
surface reconstructions for plasma-assisted molecular beam epitaxy
growth of GaN (0001) and (0 0 0 -1) surfaces are fairly well understood,
but reconstructions for reactive molecular beam epitaxy or for
metal-organic vapor phase epitaxy (both involving H, at moderate and
high temperatures, respectively) are less well understood at present.
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