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Mechanisms Affecting Emission in Rare-Earth-Activated Phosphors

Published online by Cambridge University Press:  14 March 2011

David R. Tallant ,
Carleton H. Seager  and
Regina L. Simpson
David R. Tallant
Affiliation:
Sandia National Laboratories, Albuquerque, NM, 87185-1411, U.S.A.
Carleton H. Seager
Affiliation:
Sandia National Laboratories, Albuquerque, NM, 87185-1411, U.S.A.
Regina L. Simpson
Affiliation:
Sandia National Laboratories, Albuquerque, NM, 87185-1411, U.S.A.
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Abstract

The relatively poor efficiency of phosphor materials in cathodoluminescence with low accelerating voltages is a major concern in the design of field emission flat panel displays operated below 5 kV. Our research on rare-earth-activated phosphors indicates that mechanisms involving interactions of excited activators have a significant impact on phosphor efficiency. Persistence measurements in photoluminescence (PL) and cathodoluminescence (CL) show significant deviations from the sequential relaxation model. This model assumes that higher excited manifolds in an activator de-excite primarily by phonon-mediated sequential relaxation to lower energy manifolds in the same activator ion. In addition to sequential relaxation, there appears to be strong coupling between activators, which results in energy transfer interactions. Some of these interactions negatively impact phosphor efficiency by nonradiatively de-exciting activators. Increasing activator concentration enhances these interactions. The net effect is a significant degradation in phosphor efficiency at useful activator concentrations, which is exaggerated when low–energy electron beams are used to excite the emission.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 621: Symposia Q/R – Electron-Emissive Materials, Vacuum Microelectronics… , 2000 , Q2.5.1
Copyright
Copyright © Materials Research Society 2000

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References

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