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InAs sub-monolayer quantum dots
Sub-monolayer quantum dots
are grown by alternating deposition of sub-monolayers of InAs and a
few monolayers of GaAs. In this way, a strain-induced stacking of
monolayer-high InAs patches is intended, which interact electronically
and form zero-dimensional nanostructures. In contrast to
Stranski-Krastanow quantum dots, these structures have no wetting
layer, being interesting for high-speed optoelectronic applications.
Here the atomic structure of such nanostructures grown by MOCVD was studied using XSTM . It was found that rather small structures with a very high density in the 1012/cm2 range are formed. A strong vertical segregation with segregation lengths around 1 nm is observed. In the case of thin GaAs spacer layers, this leads to vertically coherent InGaAs structures instead of the nominally assumed InAs/GaAs stacks.
- © AG Dähne
(a) XSTM image of 5layers of 0.5 ML InAs separated
by 16 layers of GaAs, and (b) variation of the local lattice constant
and therewith of the local stoichiometry indicating strong segregation
 Atomic structure of buried InAs sub-monolayer depositions in GaAs, A. Lenz, H. Eisele, J. Becker, L. Ivanova, E. Lenz, F. Luckert, K. Pötschke, A. Strittmatter, U.W. Pohl, D. Bimberg, and M. Dähne, Applied Physics Express 3, 105602 (2010).