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Coherent Clustering of GdN in Epitaxial GaN:Gd Thin Film

Published online by Cambridge University Press:  07 August 2013

Mingjian Wu ,
Steven C. Erwin  and
Achim Trampert
Mingjian Wu
Affiliation:
Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin Germany
Steven C. Erwin
Affiliation:
Center for Computational Materials Science, Naval Research Laboratory Washington, DC 20375, USA.
Achim Trampert
Affiliation:
Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin Germany
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Abstract

We present an in-depth transmission electron microscopy (TEM) study about the character of the Gd atom distribution in epitaxial GaN:Gd thin films grown by molecular beam epitaxy. High-resolution TEM (HRTEM) imaging reveals local lattice distortions of dimensions of a few atom planes only. Geometric phase analysis of HRTEM lattice images quantifies the associated displacement field. The results are explained by means of thin coherently strained GdN clusters with platelet shape being located along the basal plane. This is consistent with the observations obtained from strain contrast dark-field TEM images. Theoretically derived structure models provided by calculations based on density functional theory are used to simulate the HRTEM contrast and to determine the corresponding displacement field for matching the experimental data. Best fit is achieved in case of a coherent GdN bi-layer cluster that conclusively reflects the energy favorable configuration. The formation of the platelet clusters is explainable in the framework of spinodal decomposition.

Keywords

transmission electron microscopy (TEM)Gdthin film
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1554: Symposium U – Measurements of Atomic Arrangements and Local Vibrations in Nanostructured Materials , 2013 , mrss13-1554-u01-06
Copyright
Copyright © Materials Research Society 2013 

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References

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