An ac-type plasma display panel (ac-PDP) with K ion-doped MgO film formed via a sol-gel precursor was analyzed and compared to an ac-type PDP with MgO formed by e-beam evaporation. As the dopant content was increased, memory margins of test panels were linearly reduced and the surface charging caused by the secondary electron emission (SEE) was decreased. From these results we suggested the amounts of surface charging has a close relation to the wall potential of ac-PDP.