Published in J. Vac. Sci. Technol. B 18, 2284 (2000).
Surface structures and growth kinetics of InGaN(0001) grown by
molecular beam epitaxy
Huajie Chen,* R. M. Feenstra,* J. E. Northrup**, T. Zywietz***, J. Neugebauer*** and D. W. Greve****
*Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213
**Xerox Palo Alto Research Center, 3333 Coyote Hill Road, Palo Alto, CA 94304
***Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg
4-6, D-14195 Berlin, Germany
****Department of Electrical and Computer Engineering, Carnegie
Mellon University, Pittsburgh, Pennsylvania 15213
Abstract
The surface structures and growth kinetics of InGaN(0001) are studied.
It is well known that during molecular beam epitaxy GaN surfaces
undergo a smooth to rough transition when the growth condition is
switched from Ga-rich to N-rich. It is found here that indium atoms
have only small effect on this transition when deposited on
GaN(000-1), but when deposited on GaN(0001) the indium acts as
a surfactant and greatly extends the regime of smooth growth. Near
the smooth/rough transition of InGaN(0001) growth, a bright
rt(3)xrt(3) reconstruction is observed at growth
temperature. The formation kinetics of this reconstruction are
studied in detail. Scanning tunneling microscopy and total energy
computations are used to study the structure of InGaN(0001) surfaces
under metal rich conditions. Indium is found to occupy the top two
atomic layers of the crystal; its incorporation in the second layer
produces significant strain, leading to the formation of small pits on
the surface and increased indium concentration inside and around the
pits.
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