Scanning tunneling spectroscopy is used to investigate the single-electron states and the corresponding squared wave functions of single and freestanding strain-induced InAs quantum dots grown on GaAs(001). Several peaks are found in dI/dV curves, which belong to different single-electron states. Spatially resolved dI/dV images reveal (000), (100), (010), (200), and (300) states, where the numbers describe the number of nodes in [11;0], [110], and [001] directions, respectively. The total number and energetic sequence of states is different for different dots. Interestingly, the (010) state is often missing, even when (200) and (300) states are present. We interpret this anisotropy in electronic structure as a consequence of the shape asymmetry of the dots.

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In the paper we present the structural and morphological investigation of an InAs/AlAs(001) island system under growth conditions where partial island coalescence takes place. To provide the structural analysis of elastically strained islands, new experimental X‐ray diffraction technique based on effect of islands oxidation is proposed and verified. It is found that both elastically strained and plastically relaxed islands coexist and have distinctly different sizes and chemical composition what can be explained by differences in their formation mechanisms. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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