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Local Strain Measurements in Hexagonal Systems

Published online by Cambridge University Press:  02 July 2020

Christian Kisielowski  and
Olaf Schmidt
Christian Kisielowski
Affiliation:
National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, BerkeleyCA94720, USA
Olaf Schmidt
Affiliation:
National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, BerkeleyCA94720, USA
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It is challenging to access the microscopic distribution of strain in subsurface systems with a lateral resolution better than 1 nm and an accuracy of about 10-3 because such measurements require the detection of displacements by 1 pm at near atomic resolution. Nevertheless, such measurements are commonly desirable, in particular, for the investigations of thin heteroepitaxial films. A particular method developed in the past extracted geometrical information from unit cells in lattice images to perform this task in thin layers of cubic quantum well structures. Strain relaxation in thin TEM samples may falsify such measurements and needs to be controlled. It is the purpose of this paper to describe a quantitative method to measure strain with the required accuracy and resolution in the more complex hexagonal systems. A AxGa1-xN/GaN heterostructure grown on a sapphire substrate was investigated. Local strain comes from compositional variations which alter the size of the unit cells that are shown in Figure 1.

Type
Microscopy of Semiconducting and Superconducting Materials
Information
Microscopy and Microanalysis , Volume 4 , Issue S2: Proceedings: Microscopy & Microanalysis '98, Microscopy Society of America 56th Annual Meeting, Microbeam Analysis Society 32nd Annual Meeting, Atlanta, Georgia July 12-16, 1998 , July 1998 , pp. 614 - 615
Copyright
Copyright © Microscopy Society of America

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References

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