Regensburg 2000 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 21: Hauptvortrag
HL 21.1: Hauptvortrag
Mittwoch, 29. März 2000, 14:30–15:15, H15
Lateral and Vertical Correlations in Self-Organized Quantum Dot Superlattices — •G. Springholz1, M. Pinczolits1, V. Holy1, P. Mayer1, G. Bauer1, H.H. Kang2, and L. Salamanca-Riba2 — 1Institut fuer Halbeiterphysik, Johannes Kepler Universitaet, A-4040 Linz — 2University of Maryland at College Park, MD, USA
Strained-layer heteroepitaxy has evolved as a novel method for direct synthesis of self-assembled quantum dots, based on the Stranski-Krastanow growth mode. In multilayers of self-assembled quantum dots, the buried dots tend to influence the nucleation in the subsequent layers due to long range elastic interactions. As a result, vertical and lateral correlations within the dot ensembles are formed. In the present work, it is shown that the elastic anisotropy, typical for most semiconductors, plays a crucial role for this self-organization process, and that various types of ordered dot superstructures may be formed, depending on the surface orientation. In particular, for (111) IV-VI semiconductor dot superlattices, the interlayer correlations are found to be inclined to the growth direction. This leads to the formation of trigonally ordered 3D quantum dot crystals with fcc-like vertical dot stacking sequence and with a tunabilty of the lateral as well as vertical dot separations just by changing the spacer thickness between the dot layers. For small spacer thicknesses, however, this type of ordering is replaced by the formation of vertically aligned dot columns, similar as in other materials systems. This transition is explained by finite size effects in the elastic interactions.