High‑κ Lanthanum Zirconium Oxide Thin Film Dielectrics from Aqueous Solution Precursors

• Published in: ACS applied materials & interfaces Vol. 9; no. 12; pp. 10897 - 10903
• Main Authors: Woods, Keenan N, Chiang, Tsung-Han, Plassmeyer, Paul N, Kast, Matthew G, Lygo, Alexander C, Grealish, Aidan K, Boettcher, Shannon W, Page, Catherine J
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 29-03-2017
• Subjects: lanthanum zirconium oxide; aqueous solution deposition; dielectric; spin-coating; thin films
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.7b00915

Metal oxide thin films are critical components in modern electronic applications. In particular, high-κ dielectrics are of interest for reducing power consumption in metal–insulator–semiconductor (MIS) field-effect transistors. Although thin-film materials are typically produced via vacuum-based methods, solution deposition offers a scalable and cost-efficient alternative. We report an all-inorganic aqueous solution route to amorphous lanthanum zirconium oxide (La2Zr2O7, LZO) dielectric thin films. LZO films were spin-cast from aqueous solutions of metal nitrates and annealed at temperatures between 300 and 600 °C to produce dense, defect-free, and smooth films with subnanometer roughness. Dielectric constants of 12.2–16.4 and loss tangents <0.6% were obtained for MIS devices utilizing LZO as the dielectric layer (1 kHz). Leakage currents <10–7 A cm–2 at 4 MV cm–1 were measured for samples annealed at 600 °C. The excellent surface morphology, high dielectric constants, and low leakage current densities makes these LZO dielectrics promising candidates for thin-film transistor devices.