Degradation effect of a ZnO layer on ZnS: Comparison between a Monte Carlo simulation and experimental Auger and CL measurements

Abstract

Surface reactions occur on the ZnS:Cu,Al,Au surface during prolonged electron bombardment forming a non-luminescent ZnO layer with consequent loss in cathodoluminescence (CL) intensity. The layer is formed according to the electron-stimulated surface chemical reaction (ESSCR) mechanism. There is a direct correlation between the power emitted as luminescence and the energy loss of the electron beam. The electron energy loss within the ZnS was determined by using the Monte Carlo algorithm CASINO, which is a publicly available code. By determining the energy loss, the influence of a non-luminescent ZnO layer of varying thickness on a ZnS substrate on the CL intensity was simulated. These results were compared also with previous calculations that were based on the results of experiments done on the transmission of electrons through thin films. The energy loss within the ZnS as function of the ZnO thickness was determined at beam voltages of 1, 2 and 5 keV. The results obtained correlate with experimental CL measurements of the phosphor degradation during electron bombardment. Copyright © 2001 John Wiley & Sons, Ltd.