The cathodoluminescence generated in ZnS phosphor powder with non‐luminescent ZnS coatings: a comparison of experimental data with Monte Carlo calculations

Abstract

AbstractField emission displays (FEDs) are a possible alternative to other display technologies. They work similarly to CRTs, but instead of an electron gun they have an array of tiny metallic tips acting as electron emitters. This array is situated in close proximity to the phosphor screen and produces light by a process of cathodoluminescence (CL). During prolonged electron beam irradiation a non‐luminescent ZnO layer forms on the irradiated surface of the ZnS phosphor powder according to the electron‐stimulated surface chemical reactions (ESSCR) mechanism. The low‐energy electrons used in FEDs have a shallow penetration depth and since the CL is dependent upon the energy loss in the ZnS bulk itself, growth of the ZnO layer significantly degrades the CL intensity. Monte Carlo techniques may be used to simulate the electron trajectories and energy loss in many different types of materials. Energy loss profiles in the ZnS for different non‐luminescent ZnS coatings of known thickness were determined using the Monte Carlo electron trajectory simulations. Since only energy loss in the ZnS powder results in CL an increase in the thickness of the ZnS coating decreases the CL intensity accordingly. Simulations were performed for electron energies varying from 2 to 10 keV and at incident angles accommodating for the morphology of the phosphor powder. These results compared very well with the experimental results measured by other authors. Copyright © 2004 John Wiley & Sons, Ltd.