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Nanometer-Scale Cathodoluminescent Properties Through Z-Contrast Scanning Transmission Electron Microscopy

Published online by Cambridge University Press:  02 July 2020

H-J. Gao ,
G. Duscher ,
M. Kim ,
D. Kumar ,
R.K. Singh  and
S.J. Pennycook
H-J. Gao
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN37831-6030
G. Duscher
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN37831-6030
M. Kim
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN37831-6030
D. Kumar
Affiliation:
Department of Materials Science and Engineering, University of Florida, Gainesville, FL32611-6400
R.K. Singh
Affiliation:
Department of Materials Science and Engineering, University of Florida, Gainesville, FL32611-6400
S.J. Pennycook
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN37831-6030
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Interest in rare earth-activated oxide-based phosphor thin films for high-resolution display devices has been growing in the last few decades. However, thin-film phosphors typically have a significantly reduced brightness compared to equivalent powder phosphor materials. Several possible explanations have been suggested for the lower brightness including internal reflection and the small interaction volume between the incident beam and the solid. In this report, we show another factor to be crucial to external radiative efficiency, the porosity of the films. Porosity creates internal surfaces that act as a "dead layer" which decreases the emission efficiency. Using Z-contrast imaging in the scanning transmission electron microscope (STEM) with simultaneous cathodoluminescence (CL) imaging, the dead layer is directly observed, and quantitative accounts for the reduction of luminescent efficiency.

Eu activated Y2O3 thin films with thickness of about 200 nm were deposited on (001) LaAlO3 substrates by laser ablation. TEM analysis of the samples was conducted in a Philips EM-400 electron microscope operated at l00kV.

Type
The Theory and Practice of Scanning Transmission Electron Microscopy
Information
Microscopy and Microanalysis , Volume 6 , Issue S2: Proceedings: Microscopy & Microanalysis 2000, Microscopy Society of America 58th Annual Meeting, Microbeam Analysis Society 34th Annual Meeting, Microscopical Society of Canada/Societe de Microscopie de Canada 27th Annual Meeting, Philadelphia, Pennsylvania August 13-17, 2000 , August 2000 , pp. 130 - 131
Copyright
Copyright © Microscopy Society of America

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References

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