Properties of Ta2O3-based dielectric nanolaminates deposited by atomic layer epitaxy

Dielectric thin films and multilayers suitable for application as insulating layers in electroluminescent display devices have been studied. In this work, ZrO2-Ta2O5 and Al2O3-Ta2O5 nanolaminates with improved dielectric characteristics were grown by atomic layer epitaxy. The films were evaluated by capacitance and current voltage measurements. The pure Ta2O5, Al2O3, and ZrO2 films possessed charge-storage factors up to 8, 16, and 19 nC/mm(2), respectively at a leakage current density of 1 mu M/cm(2). The Al2O3-Ta2O5 nanolaminates were completely amorphous and their storage factors did not exceed 30 nC/mm(2). The ZrO2-Ta2O5 nanolaminates showed remarkably improved dielectric properties when compared with those of the pure oxide films, especially when the interlayer thicknesses were optimized. Nanosize crystallites of monoclinic and metastable tetragonal ZrO2 were observed in the nanolaminates by x-ray diffraction. The ZrO2-Ta2O5 nanolaminates possessed high charge-storage factors up to 64 nC/mm(2) and showed superior stability of the dielectric properties.