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Investigation of the Shape of InGaAs/GaAs Quantum Dots

Published online by Cambridge University Press:  11 February 2011

Susan Y. Lehman
Affiliation:
National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305
Alexana Roshko
Affiliation:
National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305
Richard P. Mirin
Affiliation:
National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305
John E. Bonevich
Affiliation:
National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899
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Abstract

Three samples of self-assembled In0.44Ga0.56As quantum dots (QDs) grown on (001) GaAs by molecular beam epitaxy (MBE) were studied using atomic force microscopy (AFM) and high-resolution transmission electron microscopy (TEM) in order to characterize the height, faceting, and densities of the QDs. The cross-sectional TEM images show both pyramidal dots and dots with multiple side facets. Multiple faceting has been observed only in dots more than 8.5 nm in height and allows increased dot volume without a substantial increase in base area. Addition of a GaAs capping layer is found to increase the diameter of the QDs from roughly 40 nm to as much as 200 nm. The areal QD density is found to vary up to 50 % over the central 2 cm x 2 cm section of wafer and by as much as 23 % on a length scale of micrometers.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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References

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