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Thickness Variations and Absence of Lateral Compositional Fluctuations in Aberration-Corrected STEM Images of InGaN LED Active Regions at Low Dose

Published online by Cambridge University Press:  26 March 2014

Andrew B. Yankovich*
Affiliation:
Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, WI 53706, USA
Alexander V. Kvit
Affiliation:
Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, WI 53706, USA
Xing Li
Affiliation:
Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA
Fan Zhang
Affiliation:
Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA
Vitaliy Avrutin
Affiliation:
Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA
Huiyong Liu
Affiliation:
Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA
Natalia Izyumskaya
Affiliation:
Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA
Ümit Özgür
Affiliation:
Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA
Brandon Van Leer
Affiliation:
FEI Company, Hillsboro, OR 97124, USA
Hadis Morkoç
Affiliation:
Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA
Paul M. Voyles
Affiliation:
Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, WI 53706, USA
*
*Corresponding author.ayankovich@wisc.edu
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Abstract

Aberration-corrected scanning transmission electron microscopy images of the In0.15Ga0.85N active region of a blue light-emitting diode, acquired at ~0.1% of the electron dose known to cause electron beam damage, show no lateral compositional fluctuations, but do exhibit one to four atomic plane steps in the active layer’s upper boundary. The area imaged was measured to be 2.9 nm thick using position averaged convergent beam electron diffraction, ensuring the sample was thin enough to capture compositional variation if it was present. A focused ion beam prepared sample with a very large thin area provides the possibility to directly observe large fluctuations in the active layer thickness that constrict the active layer at an average lateral length scale of 430 nm.

Type
Materials Applications
Copyright
© Microscopy Society of America 2014 

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