Quantum chemistry study of surface structure effects on secondary electron emission in MgO protecting layers for plasma displays

MgO protecting layers, which have high ion induced secondary electron emission coefficient (γ), are required in order to decrease the firing voltage of plasma displays. Theoretical estimation of ideal γ value is needed for a design of better protecting layers. In this study, we report our developed γ calculation method based on a tight-binding quantum calculation and application to an estimation of γ values of MgO protecting layers. From our calculation results, it was revealed that electron trap sites arising from surface roughness would work as an effective emission sites and increase γ value. Especially for Xe⁺ species as induced ion, the γ value changed drastically by the presence of the trapped electron. It is also suggested that a presence of chemisorbed water on the MgO surface decreases the γ values because of the contribution of the electrons at the low energy levels originated from surface OH groups.