Institute of Physics, St-Petersburg State University, Ulyanovskaya Str. 1, Peterhof 198504, St. Petersburg, Russia.
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert Einstein Str. 15, 12489, Berlin, Germany.
Sci Rep. 2017 Jul 3;7(1):4541. doi: 10.1038/s41598-017-04804-4.
Interface of TiN electrode with γ-AlO 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 AlO being converted into thermodynamically-stable polycrystalline cubic γ-phase by high-temperature (1000 or 1100 °C) anneal, our results reveal formation of a thin TiNO (≈1-nm thick) interlayer at the interface between γ-AlO film and TiN electrode due to oxygen scavenging from γ-AlO film. Formation of the TiO was not observed at this interface. As environmental effect, a strong oxidation resulting in formation of a TiO(1.4 nm)/TiNO(0.9 nm) overlayers on the top of the TiN electrode is traced. Development of O-deficiency of γ-AlO 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-AlO. This anisotropy can be correlated with ≈200 meV electron barrier height increase at the O-deficient TiN/γ-AlO interface as compared to the TiN/γ-AlO barrier formed under abundant oxidant supply condition as revealed by internal photoemission of electrons from TiN into the oxide.
采用近边 X 射线吸收精细结构、常规 X 射线光电子能谱和高能光电子能谱研究了 TiN 电极与 γ-AlO 层的界面。尽管原子层沉积的 AlO 通过高温（1000 或 1100°C）退火转化为热力学稳定的多晶立方 γ 相，但我们的结果表明，由于 γ-AlO 薄膜中的氧被消耗，在 γ-AlO 薄膜和 TiN 电极之间的界面处形成了一层很薄的 TiNO（≈1nm 厚）的中间层。在这个界面上没有观察到 TiO 的形成。作为环境效应，在 TiN 电极的顶部追踪到一个强烈的氧化作用，导致形成了 TiO(1.4nm)/TiNO(0.9nm)覆盖层。观察到 γ-AlO 中 O 缺乏的发展，并与 X 射线吸收在平行于表面的平面上涉及的自旋态的优先取向引起的极化各向异性有关。对 TiN 电极的研究表明，其结构中主要存在“拉伸”的八面体，并且相对于与 γ-AlO 的界面具有优先取向。这种各向异性可以与 O 缺乏的 TiN/γ-AlO 界面处的电子势垒高度增加约 200meV 相关，与在充足氧化剂供应条件下形成的 TiN/γ-AlO 势垒相比，这是通过 TiN 中的电子向内发射光电子揭示的。
