In this report, the optical characteristics of ZnS:Tb AC driven thin-film
electroluminescent devices are evaluated. Luminescence at low and room temperature
under a constant phosphor field is recorded in order to probe the hot electron energy
distribution. Samples fabricated by atomic layer epitaxy and by sputter deposition are
investigated and their differences and similarities evaluated. The ALE sample exhibits a
drastic increase in luminescence at low temperature, while the sputtered sample displays a
decrease in luminescence at low temperature. The reduction of optical phonon scattering
and nonradiative transition rates at low temperature are believed to be responsible for
these changes. Differences between ALE and sputtered samples are due to the different
fabrication methods. The approach suggested by Krupka in 1972 of determining the hot
electron energy distribution by taking the ratio intensities of two luminescent transitions
from different upper states in Tb�����, is shown to be inaccurate due to the possible
nonradiative transitions taking place. The Tb����� impact excitation quantum yield at a
wavelength of 489 nm is measured and is shown to agree with Monte Carlo simulations.
Saturation occurs due to the increase in band-to-band impact ionization at high phosphor
fields. / Graduation date: 1995
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/35088 |
| Date | 12 July 1994 |
| Creators | Streicher, Keone R. |
| Contributors | Plant, Thomas K. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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