Electrical and optical properties of tantalum oxide thin films prepared by reactive magnetron sputtering

• Published in: Journal of alloys and compounds 2011-10, Vol.509 (41), p.9758-9763
• Main Authors: Wei, A.X., Ge, Z.X., Zhao, X.H., Liu, J., Zhao, Y.
• Format: Article
• Language: English
• Subjects: Atomic structure; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deposition; Deposition by sputtering; Dielectric properties; Exact sciences and technology; Insulators; Magnetron sputtering; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Optical characteristics; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Oxide materials; Physics; Spectra; Tantalum oxides; Thin films; Vapor phase epitaxy; growth from vapor phase; X-ray photoelectron spectroscopy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2011.08.019

► Ta 2O 5 thin films were prepared by reactive dc magnetron sputtering. ► The structure, optical and dielectric properties of the Ta 2O 5 thin films were studied. ► The structure changed from the amorphous phase to the β-Ta 2O 5 phase after annealing at 900 °C. ► The dielectric constants and loss tangents decreased with increasing frequency. ► The refractive index of the films was 2.11 in the wavelength range 300–1000 nm. Tantalum oxide thin films were prepared by using reactive dc magnetron sputtering in the mixed atmosphere of Ar and O 2 with various flow ratios. The structure and O/Ta atom ratio of the thin films were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy (XPS). The optical and dielectric properties of the Ta 2O 5 thin films were investigated by using ultraviolet–visible spectra, spectral ellipsometry and dielectric spectra. The results reveal that the structure of the samples changes from the amorphous phase to the β-Ta 2O 5 phase after annealing at 900 °C. The XPS analysis showed that the atomic ratio of O and Ta atom is a stoichiometric ratio of 2.50 for the sample deposited at Ar:O 2 = 4:1. The refractive index of the thin films is 2.11 within the wavelength range 300–1000 nm. The dielectric constants and loss tangents of the Ta 2O 5 thin films decrease with the increase of measurement frequency. The leakage current density of the Ta 2O 5 thin films decreases and the breakdown strength increases with the increase of Ar:O 2 flow ratios during deposition.