Recent developments in surface studies of GaN and AlN

• Published in: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Vol. 23; no. 3; pp. 1174 - 1180
• Main Authors: Feenstra, R. M., Dong, Y., Lee, C. D., Northrup, J. E.
• Format: Journal Article
• Language: English
• Published: American Vacuum Society 01-05-2005
• ISSN: 0734-211X; 1520-8567; 2327-9877
• DOI: 10.1116/1.1881612

Recent developments in the structural analysis of
GaN
and
AlN
surfaces are reviewed, and the implications of these structures for molecular beam epitaxial growth are discussed. The
GaN
(
0001
)
,
AlN
(
0001
)
, and
GaN
(
10
1
¯
0
)
surfaces are all found to be terminated by metallic layers containing approximately one bilayer of
Ga
or
Al
atoms. However, in contrast to
GaN
(
0001
)
where the
Ga
bilayer exists in an incommensurate, fluid-like state at room temperature, the metallic layers for
AlN
(
0001
)
and
GaN
(
10
1
¯
0
)
form large-unit-cell commensurate structures with static atomic arrangements. Small amounts of
H
on the
GaN
(
0001
)
surface leads to facet formation on the surface, whereas larger amounts of
H
produce a
2
×
2
surface arrangement that displaces the
Ga
bilayer. A possible model for the
H
-terminated
GaN
(
10
1
¯
1
)
surface is introduced and first-principles total energy calculations employing a finite temperature thermodynamics approach are employed to determine the conditions in which it could be stable.