Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 56: Quantum dots and wires: Preparation and characterization III
HL 56.3: Vortrag
Freitag, 31. März 2006, 11:30–11:45, POT 51
Atomic structure of GaSb/GaAs quantum rings and dots studied by cross-sectional scanning tunneling microscopy — •Rainer Timm1, Andrea Lenz1, Lena Ivanova1, Holger Eisele1, Ganesh Balakrishnan2, Diana Huffaker1,2, and Mario Dähne1 — 1Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, D-10623 Berlin — 2Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106, USA
GaSb quantum dots in a GaAs matrix show a staggered type-II band alignment and are promising nanostructures for storage devices due to their large hole confinement energy [1]. Cross-sectional scanning tunneling microscopy is a powerful tool to obtain both structural and electronic information on such buried quantum dots with atomic resolution [2].
Here we present data on self-assembled GaSb/GaAs nanostructures, grown by molecular beam epitaxy. Independent of the amount of deposited GaSb ranging from 1 to 3 monolayers, we found distinctive quantum dots with truncated pyramid-like shapes with base lengths between 10 and 30 nm and 2 to 6 nm height as well as quantum rings, which have evolved from the dots by segregation of antimony out of the dot center. While the rings consist of nearly pure GaSb, strongly intermixed stoichiometries were obtained for the dots. Additionally, a shape unisotropy between the [110] and the [110] direction was observed for all structures.
This work was supported by the EU in the SANDiE Network of Excellence and by projects Da 408/8, and SFB 296 of the DFG.
[1] M. Geller et al., Appl. Phys. Lett. 82, 2706 (2003)
[2] R. Timm et al., Appl. Phys. Lett. 85, 5890 (2004)