This paper investigates the changes in the surface morphology of the MgO thin film on the ITO and bus electrodes in ac plasma display panel under various sustain voltages during the panel-aging process. it is found that the achievement in the stable discharge in an AC-PDP by means of the panel-aging process strongly depends on whether the surface morphologies of the MgO thin film are identical on both the ITO and bus electrodes. It is also found that the self-erasing discharge during the panel-aging process is not effective in obtaining the uniform surface morphology of the MgO thin film on the ITO and bus electrodes, due to the difference in the amount of ion bombardment on the ITO and bus electrodes caused by the erasing of the wall charges during the self-erasing discharge. These experimental results are confirmed by monitoring the three-dimensional IR emission and simulating the wall charge distribution, the electric field strength, and the impulse on the MgO layer. (C) 2010 Elsevier B.V. All rights reserved.