Ion-induced secondary electron emission behavior of sol-gel-derived MgO thin films used for protective layers in alternating current plasma display panels

MgO thin films were prepared using two sols (hydrolyzed sol and stabilized sol) and the ion-induced secondary electron emission behavior of the resultant thin films was investigated. A severe fluctuation in the secondary electron emission current was found in MgO films from hydrolyzed sol. The instability of the ion-induced current was due to the nanosized pores, which were formed during the topotactic reaction of Mg(OH) ₂ to MgO. Nonhydrolyzed MgO films, however, showed a stable ion-induced current. The ion-induced secondary electron emission coefficients (γ _i) of the MgO films had a maximum of 0.95±0.02 when the films were heat treated at 550°C in O ₂. The change in γ _i of nonhydrolyzed films was discussed from the viewpoint of crystallinity, residual organics, and surface roughness. The high γ _i and low processing temperature of nonhydrolyzed MgO films revealed that the sol-gel process is suitable to prepare MgO films for use as a protective layer in ac plasma display panel cells.