R. Timm

Reversed truncated cone composition distribution of In0.8Ga0.2As quantum dots overgrown by an In0.1Ga0.9As layer in a GaAs matrix

We present cross-sectional scanning tunneling microscopy results of self-organized In0.8Ga0.2As quantum dots covered by an In0.1Ga0.9As film inside a GaAs matrix prepared by metalorganic chemical vapor deposition. From images of quantum dots with atomic resolution, we determine a spatial distribution of the In composition within the dots with a shape of a reversed truncated cone. The wetting layer and the overgrown In0.1Ga0.9As layer show vertical intermixing.

Atomic structure of InAs and InGaAs quantum dots determined by cross-sectional scanning tunneling microscopy

In this work we present a comparative cross-sectional scanning tunneling microscopy study of different InAs and InGaAs quantum dot structures grown by metalorganic vapor phase epitaxy. The varying growth conditions lead to completely different spatial structures, as distinctive quantum dots, intermixed layers, and intermixed dots. Especially the overgrowth procedure and the arrangement of growth interruptions are responsible for segregation of the InAs material.

A cross-sectional scanning tunneling microscopy study of GaSb/GaAs nanostructures

We present cross-sectional scanning tunneling microscopy results of GaSb quantum wells and dots in GaAs. A fascinating potential of this technique for the investigation of overgrown nanostructures is demonstrated by revealing structural details of GaSb dots and wells with atomic resolution, by introducing a method to obtain the local stoichiometry, and by discussing different contributions to the image contrast in combination with the type-II band alignment.