Experimental evaluation of interfaces using atomic-resolution high angle annular dark field (HAADF) imaging

Robb, P., Finnie, M., Longo, P. and Craven, A. (2012) Experimental evaluation of interfaces using atomic-resolution high angle annular dark field (HAADF) imaging. Ultramicroscopy, 114, pp. 11-19. (doi: 10.1016/j.ultramic.2011.10.015)

Abstract

Aberration-corrected highangleannulardarkfield (HAADF) imaging in scanning transmission electron microscopy (STEM) can now be performed at atomic-resolution. This is an important tool for the characterisation of the latest semiconductor devices that require individual layers to be grown to an accuracy of a few atomic layers. However, the actual quantification of interfacial sharpness at the atomic-scale can be a complicated matter. For instance, it is not clear how the use of the total, atomic column or background HAADF signals can affect the measured sharpness or individual layer widths. Moreover, a reliable and consistent method of measurement is necessary. To highlight these issues, two types of AlAs/GaAs interfaces were studied in-depth by atomic-resolutionHAADFimaging. A method of analysis was developed in order to map the various HAADF signals across an image and to reliably determine interfacial sharpness. The results demonstrated that the level of perceived interfacial sharpness can vary significantly with specimen thickness and the choice of HAADF signal. Individual layer widths were also shown to have some dependence on the choice of HAADF signal. Hence, it is crucial to have an awareness of which part of the HAADF signal is chosen for analysis along with possible specimen thickness effects for future HAADF studies performed at the scale of a few atomic layers.

• Item Type: Articles
• Additional Information: NOTICE: this is the author’s version of a work that was accepted for publication in Ultramicroscopy. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Ultramicroscopy, [114, (2012)] DOI:10.1016/j.ultramic.2011.10.015
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Robb, Mr Paul and Craven, Professor Alan
• Authors: Robb, P., Finnie, M., Longo, P., and Craven, A.
• Subjects: Q Science > QC Physics
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Ultramicroscopy
• Publisher: Elsevier
• ISSN: 0304-3991
• ISSN (Online): 1879-2723
• Published Online: 04 November 2011
• Copyright Holders: Copyright © 2012 Elsevier
• First Published: First published in Ultramicroscopy 114:11-19
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher