- Relative Quantum Efficiencies of Phosphor Powders and Films
R.S. Meltzer and W.M Dennis
Research Objectives
- Obtain the spectrum of the relative quantum efficiencies of phosphors
under vacuum UV excitation. The goal is to optimize phosphors for excitation
with a plasma display source and distinguish the efficiency for the 147 nm and
170 nm Xe plasma lines so that phosphors and plasma sources can be
co-optimized.
- Obtain alternative plasma display green phosphors with shorter radiative
lifetimes to replace Zn2SiO4:Mn whch is too slow for many types of displays.
- Obtain blue and red plasma display phosphors with higher quantum
efficiencies than the currently used BAM and YGdBO3:Eu.
- Compare the relative efficiencies of phosphors under photoluminescent and
electron beam excitation.
- Examine the effects of thin film geometry on phosphor efficiency. The
effect of surfaces, substrates (conducting, semiconducting and insulating),
and nearby layers will be examined.
- Characterization and Minimization of Aging of Phosphors
R.S. Meltzer, W.M. Dennis and William M. Yen
Research Objectives
- Characterize aging of phosphor samples under plasma display excitation.
Aged samples will be supplied by Electroplasma and Photonics. The goal is to
reduce and minimize the effects of aging.
- Aging studies in small single crystal samples prepared by laser-heated
pedestal growth. Comparisons will be made with aging of powder samples of the
same materials. The goal is to distinguish bulk and surface effects.
- Study aging under electron beam excitation. Aging will be done at both
high and low beam energies.
- Determination of Phosphor Lifetimes and Energy Transfer Processes
W.M. Dennis, U. Happek, R.S. Meltzer and W.M. Yen
The objective of this project is to gain a more detailed understanding of the
excitation and relaxation dynamics of phosphor materials. Both linear and
nonlinear time resolved spectroscopic techniques are utilized. Linear
techniques include time correlated photon counting, nonlinear techniques
include pump and probe. In addition to optical excitation, fluorescent
transients can be measured under CR excitation with nanosecond time
resolution. Photoconductivity measurements are used to study the properties
of phosphors with dynamics that are determined by the relative position of
the energy levels in the band gap.
Post Doctoral Associate: Dr. Kiwan Jang
Graduate Research Assistant: Dean Evans
- Development of New Low-Voltage FED Phosphors
W.M. Dennis, W.M Yen, in conjunction with P.N. Yocom, David Sarnoff
Research Institute and S.M. Jacobsen, Georgia Institute of Technology,
Research Institute
The objective of this project is to develop and characterize new FED
phosphors by engineering both powder and thin film structures that will
exhibit improved low voltage characteristics and surface stability.
Graduate Research Assistants: Dean Evans, Garfield Warren, T. Song
- Synthesis of Low-Voltage Field Emission Display Phosphors
W.M. Yen, W.M. Dennis and J.L. Stickney
The objective of this project is to synthesize "benchmark" phosphors in a
form appropriate for FED applications. The influence of composition (sulphur
richness) and particle size on the CL efficiency will be investigated.
Graduate Research Assistants: Dean Evans, G. Warren, R. Herrick
- FED Phosphor Surface Modification
J. Stickney, Robert Herrick
This project involves studies of the energy dependence of luminescence at
low voltages (5KV and below). Can wet etching or deposition be used to modify
the surface of phosphor particles in order to improve the luminescence at low
voltages.
A UHV surface analysis instrument has been equipped to perform CL studies of
phosphor materials supported on flat substrates. The instrument includes a
reaction chamber where clean substrate can be coated with phosphors, which
have been chemically etched, all without exposure to air.
Current Projects