Strain analysis of Ge micro disk using precession electron diffraction

Bashir, A., Millar, R. W. , Gallacher, K. , Paul, D. J. , Darbal, A. D., Stroud, R., Ballabio, A., Frigerio, J., Isella, G. and MacLaren, I. (2019) Strain analysis of Ge micro disk using precession electron diffraction. Journal of Applied Physics, 126, 235701. (doi: 10.1063/1.5113761)

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The recently developed precession electron diffraction (PED) technique in scanning transmission electron microscopy has been used to elucidate the local strain distribution and crystalline misorientation in a CMOS fabricated strained Ge microdisk structure grown on a Si substrate. Tensile strained Ge and GeSn structures are considered to be potential CMOS compatible optical sources, as both Sn alloying and strain can lead to a direct band-structure and lasing. The ability to take nanometer resolution, experimental measurements of the cross-sectional strain distribution, is important to understand modal gain and, therefore, ultimate device performance. In this work, we demonstrate PED techniques to measure the cross-sectional strain field in tensile Ge microdisks strained by SiN stressors. The strain maps are interpreted and compared with a finite element model of the strain in the investigated structure, which shows good agreement, and, therefore, highlights the applicability of PED techniques for mapping strained photonic structures. The technique also allows for the observation of strain relaxation due to dislocation pileup, further demonstrating the benefit of such experimental techniques.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Millar, Dr Ross and MacLaren, Dr Ian and Bashir, Ms Aneeqa and Paul, Professor Douglas and Gallacher, Dr Kevin
Authors: Bashir, A., Millar, R. W., Gallacher, K., Paul, D. J., Darbal, A. D., Stroud, R., Ballabio, A., Frigerio, J., Isella, G., and MacLaren, I.
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
College of Science and Engineering > School of Physics and Astronomy
Research Group:Geometry & Topology
Journal Name:Journal of Applied Physics
Publisher:American Institute of Physics
ISSN (Online):1089-7550
Published Online:16 December 2019
Copyright Holders:Copyright © 2019 American Institute of Physics
First Published:First published in Journal of Applied Physics 126:235701
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
171911Engineering Quantum Technology Systems on a Silicon PlatformDouglas PaulEngineering and Physical Sciences Research Council (EPSRC)EP/N003225/1ENG - Electronics & Nanoscale Engineering