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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 7: Microstructure of thin films / TEM-based Nanoanalysis

KFM 7.9: Vortrag

Montag, 12. März 2018, 18:00–18:20, E 124

Structural properties of InGaAs Quantum dots investigated by Transmission Electron Microscopy — •Laura Meißner, Tore Niermann, and Michael Lehmann — Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17.Juni 135, Berlin, Deutschland

Optical characteristics of semiconductor quantum dots (QDs) depend closely on their structural properties, like composition, shape, and strain state. By controlling the growth process, these structural properties can be changed and in turn the optical properties are improved. In order to understand the behaviour of the QDs these structural properties have to be monitored.

We report on investigations of composition and strain of InGaAs QDs embedded in GaAs by means of Transmission Electron Microscopy. Microscopic techniques like Geometric Phase Analysis and Dark-field-Electron-Holography are employed to record amplitude and phase of different reflected beams.

In order to avoid relaxation effects and hence observe the strain field of the QDs in a bulk-like state, thick samples (over 100 nm) must be investigated. For these conditions, we discuss the effects of dynamic diffraction on the reflection specific sensitivity to composition and strain.