Published in J. Cryst. Growth 209, 355 (2000).
Structure of Clean and Arsenic-covered GaN(0001) Surfaces
V. Ramachandran, C. D. Lee, and R. M. Feenstra
Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania
15213
A. R. Smith
Department of Physics and Astronomy,
Ohio University, Athens, Ohio 45701
J. E. Northrup
Xerox Palo Alto Research Center, 3333 Coyote Hill Road, Palo
Alto, California 94304
D. W. Greve
Department of Electrical and Computer Engineering, Carnegie
Mellon University,
Pittsburgh, Pennsylvania 15213
Abstract
The effect of trace arsenic on the growth and surface structure of
GaN(0001) has been studied. We find that a partial pressure of only
10-9 Torr of arsenic during molecular beam epitaxial growth
significantly modifies the growth kinetics. Such a small background
pressure of arsenic leads to an arsenic-terminated surface displaying
a 2x2 reconstruction during growth which is
absent for the clean surface. First-principles theoretical
calculations show that As-terminated surfaces are energetically more
favorable than Ga-terminated surfaces for arsenic pressures of
10-9 Torr, and structural models for the
As-adatom 2x2 reconstruction are presented.
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