Nanocrystalline polymorphic oxide perovskite-based high-κ low-leakage thin film materials

Abstract

We report on thin-film nanocrystalline polymorphic BaTiO3 for enabling high dielectric and low leakage response. BaTiO3-Al2O3 bi-layer thin films based on nanocrystalline BaTiO3 containing the tetragonal and hexagonal polymorphs were deposited by atomic layer deposition. Polymorphic BaTiO3 film combined with a ≈ 3.5-nm thick Al2O3 layer located between the BaTiO3 film and top electrode exhibits dielectric constant of 108 or 130 and leakage currents 2.2 × 10−8 A/mm2 or 1.3 × 10−7 A/mm2 at 1 MV/cm, respectively. Where x-ray photoemission analysis of barrier heights for the metal-BaTiO3-Al2O3-metal structure point to using the polymorphic BaTiO3 interspersed between Al2O3 layers in tri-layered dielectric thin film capacitors, the outstanding combination of high dielectric constant and low leakage current for the polymorphic BaTiO3 - Al2O3 thin film stacks is superior to common high-κ polycrystalline thin film materials.