InAs quantum dot and wetting layer formation in GaAs and AlAs analyzed by cross-sectional scanning tunneling microscopy

P. Offermans, P.M. Koenraad, J.H. Wolter, K. Pierz, M. Roy, P.A. Maksym

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Cross-sectional scanning-tunneling microscopy (X-STM) has been used to study the formation of self-assembled InAs quantum dots (QDs) and wetting layers on AlAs (100) and GaAs (100) surfaces. On AlAs we find a larger QD density and smaller QD size than for QDs grown on GaAs under the same growth conditions (500°C substrate temperature and 1.9 ML indium deposition). We have determined the indium composition of the QDs by fitting it to the measured outward relaxation of the cleaved surface using a three-dimensional finite element calculation based on elasticity theory. The QDs grown on GaAs show both a normal and a lateral gradient in the indium distribution whereas the QDs grown on AlAs show only a normal gradient. No significant differences in the segregated In-profiles for the wetting layers on GaAs and AlAs are observed. We suggest that the segregation of the wetting layer is mainly strain-driven, whereas the formation of the QDs is also determined by growth-kinetics.
Originele taal-2Engels
Pagina's (van-tot)1-13
Aantal pagina's13
TijdschriftPhysics of Low Dimensional Structures
Volume1/2
Nummer van het tijdschrift1/2
StatusGepubliceerd - 2004

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