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

• Published in: Thin solid films Vol. 709; p. 138123
• Main Authors: Golovina, Iryna S., Falmbigl, Matthias, Plokhikh, Aleksandr V., Bennett-Jackson, Andrew L., Ruffino, Anthony J., Gutierrez-Perez, Alejandro D., Johnson, Craig L., Spanier, Jonathan E.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2020
• Subjects: Atomic layer deposition; Barium titanate; High-κ materials; Metal-insulator-metal capacitor; Oxide thin films; Oxide thin films; Barium titanate; High-κ materials; Atomic layer deposition; Metal-insulator-metal capacitor
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2020.138123

•Utilizing a seed layer results in a nanocrystalline polymorphic BaTiO3 thin film.•A 3.5-nm thick Al2O3 layer reduces leakage current by 5 orders in BaTiO3-Al2O3.•Superior combination of high dielectric constant and low leakage current is shown. 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.