AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS-ThP

Paper SS-ThP2
Cathodoluminescence Degradation of SiO@sub 2@:Ce,Tb Powder Phosphors Prepared by a Sol-Gel Process

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Surface Science Poster Session
Presenter: O.M. Ntwaeaborwa, University of the Free State, South Africa
Authors: O.M. Ntwaeaborwa, University of the Free State, South Africa
H.C. Swart, University of the Free State, South Africa
R.E. Kroon, University of the Free State, South Africa
P.H. Holloway, University of Florida
Correspondent: Click to Email
Auger electron spectroscopy (AES), cathodoluminescence (CL) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to study degradation of the CL intensity of SiO@sub 2@:Ce,Tb powder phosphors prepared by a sol-gel process. The AES and CL data were collected simultaneously when the powders were irradiated for 10 hours with a beam of electrons of energy 2 keV and a current density of 54 mA/cm@super 2@ in an ultra high vacuum chamber containing either 1x10@super -8@ or 1x10@super -7@ Torr O@sub 2@. A decrease of CL intensity during electron beam bombardment occurred simultaneously with desorption of oxygen from the surface, i.e. there is a correlation between the degradation of CL intensity and desorption of oxygen. The AES and XPS data suggest that a non-luminescent oxygen-deficient layer of SiO@sub x@ (x<2)was formed on the surface and resulted in the decrease of CL intensity. The formation of the SiO@sub x@ layer is consistent with an electron stimulated surface chemical reaction (ESSCR) model. Mechanisms by which oxygen desorption leads to a reduction of the CL intensity are discussed.