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Open Access Nano Express

Can misfit dislocations be located above the interface of InAs/GaAs (001) epitaxial quantum dots?

Zi-Bin Chen1, Wen Lei2, Bin Chen1, Yan-Bo Wang1, Xiao-Zhou Liao1*, Hoe H Tan3, Jin Zou4, Simon P Ringer15 and Chennupati Jagadish3

Author Affiliations

1 School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales, 2006, Australia

2 School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Perth, Western Australia, 6009, Australia

3 Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, Australian Capital Territory, 0200, Australia

4 Materials Engineering and Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland, 4072, Australia

5 Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales, 2006, Australia

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Nanoscale Research Letters 2012, 7:486  doi:10.1186/1556-276X-7-486

Published: 31 August 2012

Abstract

InAs/GaAs(001) quantum dots grown by droplet epitaxy were investigated using electron microscopy. Misfit dislocations in relaxed InAs/GaAs(001) islands were found to be located approximately 2 nm above the crystalline sample surface, which provides an impression that the misfit dislocations did not form at the island/substrate interface. However, detailed microscopy data analysis indicates that the observation is in fact an artefact caused by the surface oxidation of the material that resulted in substrate surface moving down about 2 nm. As such, caution is needed in explaining the observed interfacial structure.

Keywords:
Quantum dot; Electron microscopy; Misfit dislocations; Droplet epitaxy; Oxidation