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Characterization of Crystal Polarity Across Twin Boundaries in GaP

Published online by Cambridge University Press:  02 July 2020

Dov Cohen ,
Stuart McKernan  and
C. Barry Carter
Dov Cohen
Affiliation:
Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue South East, Minneapolis, MN55455
Stuart McKernan
Affiliation:
Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue South East, Minneapolis, MN55455
C. Barry Carter
Affiliation:
Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue South East, Minneapolis, MN55455
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The measurement of the absolute crystal polarity is crucial to understanding the structural properties of planar defects in the sphalerite structure. Due to the directionality of the chemical bond between cations and anions in this lattice, grain boundaries in sphalerite can be described by two distinct structural models. Each model is distinguished by the relative orientation of the polar axis in the grains adjoining the interface. In order to evaluate the polarity of twinned grains in GaP, a dynamical diffraction technique is used to determine the Ga to P bond direction across a coherent twin boundary.

The characterization of the polarity in GaP was performed using a convergent-beam electron diffraction technique developed by Tafto and Spence.CBED can be used to identify the direction of the crystal polarity by observing asymmetries in dynamical diffraction contrast in reflections from crystal planes of opposite polarity. Such contrast arises when the Ewald sphere intercepts a weak {002} reflection plus two or more higher order, odd indexed reflections.

Type
Recent Developments in Microscopy for Studying Electronic and Magnetic Materials
Information
Microscopy and Microanalysis , Volume 3 , Issue S2: Proceedings: Microscopy & Microanalysis '97, Microscopy Society of America 55th Annual Meeting, Microbeam Analysis Society 31st Annual Meeting, Histochemical Society 48th Annual Meeting, Cleveland, Ohio, August 10-14, 1997 , August 1997 , pp. 491 - 492
Copyright
Copyright © Microscopy Society of America 1997

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References

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