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Free keywords:
Molecular-Beam Epitaxy; High-Index Surfaces; Optical Characterization; Atomic-Structure; (311)B GaAs; Shape; Islands; Reconstruction; Heteroepitaxy; Morphology
Abstract:
InAs quantum dots (QD's) were grown on GaAs(113)A and GaAs((1) over bar(1) over bar(3) over bar )B substrates by molecular-beam epitaxy. Atomically resolved scanning tunneling microscopy images acquired in situ from uncapped samples reveal the shape of the QD's including the atomic structure of their main bounding facets. On the (113)A substrate the QD's are elongated along [33 (2) over bar] with a wide size distribution, whereas on ((1) over bar(1) over bar(3) over bar )B they are rather round and exhibit a more uniform size distribution. These observations are related to the different morphology of the substrates before QD formation. The differences in shape, size, and size distribution are discussed in terms of facet growth kinetics.
