The use of TiON films by plasma-enhanced atomic layer deposition as insulators in thin film electroluminescent (TFEL) devices was examined and compared with that of TiO2 by ALD. A ZnS:Mn TFEL device using AlON-TiON stacked insulator (ATON) exhibited the figure of merit of 12 muC/cm(2). The luminance of the TFEL device with an ATON insulator was twice as high as that with a conventional Al2O3 insulator. This high performance can be attributed not only to high dielectric constant of the ATON film, but the improved quality of the interface of the phosphor and insulator, as well. (C) 2004 The Electrochemical Society.