Supplementary Material for "Correlating structure, strain and morphology
of self-assembled InAs quantum dots on GaAs "
D.P. Kumah,1* J.H. Wu,2 N.S. Husseini,1 V.D. Dasika,2 R.S. Goldman,2, 3 Y.
Yacoby,4 and R. Clarke1, 3
1)
Applied Physics Program, University of Michigan, Ann Arbor, MI 48109,
USA
2)
Department of Materials Science and Engineering, University of Michigan,
Ann Arbor, MI 48109,USA
3)
Center for Solar and Thermal Energy Conversion, University of Michigan,
Ann Arbor, MI 48109,USA
4)
Racah Institute of Physics, Hebrew University, Jerusalem 91904,
Israel
* current affliation: Yale University, New Haven, CT 06511, USA
The InAs QDs were grown on epi-ready [001] oriented GaAs substrates by molecular
beam epitaxy, using solid Ga, In, and As4 sources. The substrate temperature was
monitored during growth using an optical pyrometer. An initial 500 nm thick GaAs
buffer layer was grown at 580o C with a V/III beam-equivalent pressure ratio of 30. The
GaAs buffer was annealed at 580o C with As4 followed by annealing at 530o C with half
the original As4 flux. After the buffer annealing treatment, 2.6 ML of InAs was deposited
at 500o C, forming a high density of uniform QDs.1 The 2D-3D transition was evidenced
by a transition in the reflection high-energy electron diffraction pattern from streaks to
spots. Atomic force measurements (see Fig. S1) show that the QDs have high uniformity
in shape and size with a density of 6.4±0.3x1010 QDs/cm2. The QD heights are 3.8±0.5
nm and widths of 20±5 nm.
FIG S1: 1 m x 1 m AFM image of Stranski-Krastanow InAs dots grown on GaAs by
molecular beam epitaxy.
REFERENCES
1
W. Ye, S. Hanson, M. Reason, X. Weng, and R. S. Goldman, J. Vac. Sci. Technol. B 23,
1736 (2005).