Re-distribution of oxygen at the interface between γ-Al2O3 and TiN

• Published in: Scientific reports Vol. 7; no. 1; pp. 1 - 14
• Main Authors: Filatova, E. O., Konashuk, A. S., Sakhonenkov, S. S., Sokolov, A. A., Afanas’ev, V. V.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 03.07.2017; Nature Publishing Group UK; Nature Portfolio
• Subjects: Anisotropy; Electrodes; Oxidation; Oxygen; Photoelectron spectroscopy; Spectroscopy; Spectrum analysis; Ultrastructure; X-rays
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-04804-4

Abstract Interface of TiN electrode with γ-Al 2 O 3 layers was studied using near edge X-ray absorption fine structure, conventional X-ray photoelectron spectroscopy and photoelectron spectroscopy with high energies. Despite the atomic-layer deposited Al 2 O 3 being converted into thermodynamically-stable polycrystalline cubic γ-phase by high-temperature (1000 or 1100 °C) anneal, our results reveal formation of a thin TiN x O y (≈1-nm thick) interlayer at the interface between γ-Al 2 O 3 film and TiN electrode due to oxygen scavenging from γ-Al 2 O 3 film. Formation of the TiO 2 was not observed at this interface. As environmental effect, a strong oxidation resulting in formation of a TiO 2 (1.4 nm)/TiN x O y (0.9 nm) overlayers on the top of the TiN electrode is traced. Development of O-deficiency of γ-Al 2 O 3 is observed and related to the polarization anisotropy due to the preferential orientation of spin states involved in the X-ray absorption in the plane parallel to the surface. Investigation of the TiN electrode reveals the predominantly “stretched” octahedra in its structure with the preferential orientation relative the interface with γ-Al 2 O 3 . This anisotropy can be correlated with ≈200 meV electron barrier height increase at the O-deficient TiN/γ-Al 2 O 3 interface as compared to the TiN/γ-Al 2 O 3 barrier formed under abundant oxidant supply condition as revealed by internal photoemission of electrons from TiN into the oxide.