Uniform Nanoscale SiO[sub 2] Encapsulation of ZnS Phosphors for Improved Aging Properties under Low Voltage Electron Beam Excitation

Abstract

A significant improvement (220%) is reported in the low voltage (2000 V) aging characteristics under cathodoiuminescence (CL) excitation for ZnS phosphors coated with 1.0 wt % SiO 2 by the sol-gel technique. The formation of nanoscale uniform coating was confirmed by structural analysis. An improvement in chemical and thermal stability was also confirmed by chemical etching and heat-treatment of the SiO 2 -coated phosphors. Also, the CL aging study showed a much improved CL efficiency curve for the SiO 2 -coated ZnS phosphors. The Auger electron spectroscopy study showed that the SiO 2 -coated phosphors were far more resistant to the loss of S species and to the formation of oxide dead layer. The structural, chemical, and CL characterizations demonstrated that the thin and uniform SiO 2 layers on ZnS phosphors served as protective layers retarding the surface-related degradation, which is critically important for the development of commercial field emission displays. © 2001 The Electrochemical Society. All rights reserved.