Two protecting layers, a MgF2/MgO multilayer coated MgO layer and a LaF3 layer coated MgO layer, were studied in order to overcome the weakness of the conventional MgO protecting layer for use in color alternating current (ac) plasma display panels (PDPs). The material characteristics of these protecting layers were examined by carefully changing the growing conditions. The display characteristics were also examined by manufacturing real PDPs using these protecting layers. These two protecting layers had higher secondary electron-emission yields than conventional MgO. It was demonstrated that these two methods were effective for lowering the firing and sustaining voltage of PDPs and also for enhancing the brightness of the panel. (C) 2003 American Vacuum Society.