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Cracking self-assembled InAs quantum dots

Cracking self-assembled InAs quantum dots We present a cross-sectional scanning tunneling microscopy (X-STM) investigation of InAs quantum dots in a GaAs matrix. The structures were grown by molecular beam epitaxy (MBE) at a low growth rate of 0.01 ML/s and consist of five layers of uncoupled quantum dot structures. Detailed STM images with atomic resolution show that the dots consist of an InGaAs alloy and that the indium content in the dot increases towards the top. The analysis of the height versus base-length relation obtained from cross-sectional images of the dots shows that the shape of the dots resembles that of a truncated pyramid and that the square base is oriented along the [010] and [100] directions. Using scanning tunneling spectroscopy (STS) we determined the onset for electron tunneling into the conduction and out of the valence band, both in the quantum dots and in the surrounding GaAs matrix. We found equal voltages for tunneling out of the valence band in GaAs or InGaAs whereas tunneling into GaAs occurred at higher voltages than in InGaAs. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Applied Physics A: Materials Science Processing Springer Journals

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Publisher
Springer Journals
Copyright
Copyright © 2001 by Springer-Verlag
Subject
Physics; Condensed Matter Physics; Optical and Electronic Materials; Nanotechnology; Characterization and Evaluation of Materials; Surfaces and Interfaces, Thin Films; Operating Procedures, Materials Treatment
ISSN
0947-8396
eISSN
1432-0630
DOI
10.1007/s003390100663
Publisher site
See Article on Publisher Site

Abstract

We present a cross-sectional scanning tunneling microscopy (X-STM) investigation of InAs quantum dots in a GaAs matrix. The structures were grown by molecular beam epitaxy (MBE) at a low growth rate of 0.01 ML/s and consist of five layers of uncoupled quantum dot structures. Detailed STM images with atomic resolution show that the dots consist of an InGaAs alloy and that the indium content in the dot increases towards the top. The analysis of the height versus base-length relation obtained from cross-sectional images of the dots shows that the shape of the dots resembles that of a truncated pyramid and that the square base is oriented along the [010] and [100] directions. Using scanning tunneling spectroscopy (STS) we determined the onset for electron tunneling into the conduction and out of the valence band, both in the quantum dots and in the surrounding GaAs matrix. We found equal voltages for tunneling out of the valence band in GaAs or InGaAs whereas tunneling into GaAs occurred at higher voltages than in InGaAs.

Journal

Applied Physics A: Materials Science ProcessingSpringer Journals

Published: Apr 1, 2001

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