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

Paper FP-TuM10
Aging and Luminescent Characterization of Coated ZnS:Ag Phosphors in FED Systems

Tuesday, October 3, 2000, 11:20 am, Room 313

Session: Luminescent Materials
Presenter: G.R. Villalobos, Naval Research Laboratory
Authors: G.R. Villalobos, Naval Research Laboratory
J.S. Sanghera, Naval Research Laboratory
I. Aggarwal, Naval Research Laboratory
Correspondent: Click to Email
Sulfide phosphors used in field emission displays (FED) tend to degrade (both physical and luminescent degradation) from interaction with the emitted electrons and residual gases in the device vacuum. A variety of coating types may protect the phosphors from degradation. For example, inert buffer coatings can isolate the phosphor from the residual gases in the device vacuum, electrically conductive coatings can reduce the surface charging, and thermally conductive coatings could reduce the heating from the electron beam on the phosphor surface. It is also possible that a layered structure composed of these individual coatings could be of benefit. We have scaled up a process that we developed to hermetically coat individual phosphor particles with various films. Whereas the laboratory-sized process could coat a half-gram of phosphor per day, the pilot plant scale system can coat up to 100 grams per day without a reduction in luminescent properties. To date we have deposited SiO@sub 2@, MgO, ITO, and Na(PO@sub 3@)@sub 6@ coatings on ZnS:Ag phosphors. The process allows a precise control over the thickness of the coating. Coating thicknesses of 5 to 90nm have been achieved. The process is continuous, is fully automated, and further scaleable to industrial sizes. The cathodoluminescent (CL) efficiency and aging behavior of the SiO@sub 2@ coated phosphor has been measured in both laboratory and FED devices. Aging tests have shown a dramatic improvement in aging behavior between the coated and un-coated phosphors. While phosphor efficiency and chromaticity are within 10% of uncoated values. Future work will include the measurement of the other coating materials.