Nanolaminated Ta2O5–Al2O3 Insulator Effect on Luminescent and Electrical Properties of Thin-Film Electroluminescent Devices

Abstract

Three ZnS:Tb alternating-current thin-film electroluminescent (ACTFEL) devices were fabricated with different insulator structures by utilizing nanolaminated Ta2O5–Al2O3 and/or Al2O3. These devices were grown by sequential atomic-layer-deposition processes for bottom insulator, phosphor, and top insulator layers. The nanolaminated ACTFEL device with two Ta2O5–Al2O3 insulators were found to have low onset voltages, 50 V less than that of the Al2O3 device, for inducing conductive charge transfer and concomitant electroluminescence. The devices with the nanolaminated insulator showed more excessive dynamic space charge generation within the phosphor than the Al2O3 device. These insulator-dependent features and various observed electrical responses have been discussed in terms of the difference in the relative dielectric constants of used insulators (7 for Al2O3 and 15 for Ta2O5–Al2O3), and the creation mechanism of dynamic space charge.