Process development of halide transport chemical vapor deposited (HTCVD)
ZnS:Mn thin film has been studied. To this end, electrical characterization of HTCVD
ZnS:Mn electroluminescent devices has been used. Process optimization focused on a
simple design of experiment (DOE) with brightness as the major response.
Deposition parameters such as HCl and H���S gas flow rates, ZnS and Mn source
temperatures and substrate temperature were studied. A substrate temperature of 550��C gives the brightest devices. ZnS source temperature and H���S gas flow rate are
insignificant parameters according to the statistical analysis. However HCl gas flow
rate and Mn source temperature show strong interaction. It is proposed that the
incorporation of Cl into the ZnS:Mn film causes the interaction. A Cl defect is also
consistent with anomalous electrical behavior observed in the devices. Cl defects are
thought to precipitate at the grain boundaries of the initial growth interface, then
diffuse (or migrate) along the grain boundaries and possibly into the bulk crystal. This
defect will easily form negative charge leading to asymmetric space charge in the bulk of the phosphor.
Since the defects are believed to originate from the nucleation of Cl at high grain boundary density, one potential solution is to remove the Cl source as the grains begin to grow and only later expose the film to Cl. While film growth without HCl present at the beginning of deposition leads to brighter films, it is a sub-optimal solution. Part of the ZnS host does not have luminescent centers. It is believed other processing solutions need to be realized to make the HTCVD system viable. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33619 |
| Date | 18 June 1998 |
| Creators | Husurianto, Sjamsie |
| Contributors | Koretsky, Milo D. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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