Modelling of AlAs/GaAs interfacial structures using high-angle annular dark field (HAADF) image simulations

Robb, P.D., Finnie, M. and Craven, A. (2012) Modelling of AlAs/GaAs interfacial structures using high-angle annular dark field (HAADF) image simulations. Ultramicroscopy, 118, pp. 53-60. (doi: 10.1016/j.ultramic.2012.05.001)

Abstract

High angle annular dark field (HAADF) image simulations were performed on a series of AlAs/GaAsinterfacial models using the frozen-phonon multislice method. Three general types of models were considered—perfect, vicinal/sawtooth and diffusion. These were chosen to demonstrate how HAADFimage measurements are influenced by different interfacialstructures in the technologically important III–V semiconductor system. For each model, interfacial sharpness was calculated as a function of depth and compared to aberration-corrected HAADF experiments of two types of AlAs/GaAs interfaces. The results show that the sharpness measured from HAADF imaging changes in a complicated manner with thickness for complex interfacialstructures. For vicinal structures, it was revealed that the type of material that the probe projects through first of all has a significant effect on the measured sharpness. An increase in the vicinal angle was also shown to generate a wider interface in the random step model. The Moison diffusion model produced an increase in the interface width with depth which closely matched the experimental results of the AlAs-on-GaAs interface. In contrast, the interface width decreased as a function of depth in the linear diffusion model. Only in the case of the perfect model was it possible to ascertain the underlying structure directly from HAADFimage analysis.

• 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, [118, (2012)] DOI:10.1016/j.ultramic.2012.05.001
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Robb, Mr Paul and Craven, Professor Alan
• Authors: Robb, P.D., Finnie, M., 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: 14 May 2012
• Copyright Holders: Copyright © 2012 Elsevier
• First Published: First published in Ultramicroscopy 118:53-60
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher