AVS 47th International Symposium
    Flat Panel Displays Tuesday Sessions
       Session FP-TuM

Paper FP-TuM6
Effect of He/Ar Sputtering Gas Mixture on the Brightness of RF Magnetron-Sputtered ZnS:TbOF for Alternating Current Electroluminescent Displays

Tuesday, October 3, 2000, 10:00 am, Room 313

Session: Luminescent Materials
Presenter: J.P. Kim, University of Florida
Authors: J.P. Kim, University of Florida
M. Davidson, University of Florida
D. Moorehead, University of Florida
P.H. Holloway, University of Florida
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ZnS:TbOF has shown promise as a green electroluminescent phosphor. We have studied the effects of He/Ar mixture as ambient gas on the brightness of ZnS:TbOF thin film electroluminescent devices. ZnS:TbOF phosphor films were planar magnetron sputter deposited from consolidated powder targets of ZnS:TbOF (1.5 mol %) at 120W. All films were deposited at a substrate temperature of 160°C and total pressure of He/Ar gas was kept at 20mTorr. Helium gas ratio was changed from 0% to 70%. Top insulator layer was planar magnetron sputter deposited from consolidated powder targets of BaTa@sub 2@O@sub 6@. The sputtering deposition rate of ZnS:TbOF was in the range of 84Å/min - 113Å/min and was not changed significantly by increasing the He/Ar ratio. He/Ar gas mixture up to 50% He don't result in any significant change of the brightness (B@sub 40@@super half@) of half stack structures (bottom dielectric layer and top Al dot contact directly on the ZnS:TbOF) for either as-deposited or annealed films (500 °C,60 min). At a higher helium ratio (> 60%), the B@sub 40@@super half@ decreased for both as-deposited and annealed films (500 °C, 60 min). Surface roughness was less for >60% He, as measured by Atomic Force Microscopy (AFM). Full Width of Half Maximum (FWHM) from X-ray diffraction showed increased crystallinity of deposited film > 60% He. Films deposited at > 60% He exhibited higher dielectric constants. Therefore, the brightness decrease in high helium is attributed to reduced roughness and increased dielectric constant of the phosphor layer. This work was supported by DARPA Grant MDA 972-932-1-0030 through the Phosphor Technology Center of Excellence.