XPS analysis for degraded Y2SiO5:Ce phosphor thin films

X-ray photoelectron spectroscopy (XPS) results were obtained for standard Y2SiO5:Ce phosphor powders as well as undegraded and 144 h electron degraded Y2SiO5:Ce pulsed laser deposited (PLD) thin films. The two Ce 3d peaks positioned at 877.9 ± 0.3 and 882.0 ± 0.2 eV are correlated with the two different sites occupied by Ce in the Y2SiO5 matrix. Ce replaced the Y in the two different sites with coordination numbers of 9 and 7. The two Ce 3d XPS peaks obtained during the thin film analysis were also correlated with the luminescent mechanism of the broad band emission spectra of the Y2SiO5:Ce X1 phase. These two different sites are responsible for the two main sets of cathodoluminescent (CL) and photoluminescence (PL) peaks situated at wavelengths of 418 and 496 nm. A 144 h electron degradation study on the Y2SiO5:Ce thin film yielded an increase in the CL intensity with a second broad emission peak emerging between 600 and 700 nm. XPS analysis showed the presence of SiO2 on the surface that formed during prolonged electron bombardment. The electron stimulated surface chemical reaction (ESSCR) model is used to explain the formation of this luminescent SiO2 layer.