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

Abstract

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.