Lead-Free 伪-La2WO6 Ferroelectric Thin Films

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• 作者：Thomas Carlier ; Marie-H茅l猫ne Chambrier ; Anthony Ferri ; Sonia Estrad茅 ; Jean-Fran莽ois Blach ; Gemma Mart铆n ; Belkacem Meziane ; Francesca Peir贸 ; Pascal Roussel ; Freddy Ponchel ; Denis R猫miens ; Albert Cornet ; Rachel Desfeux
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：November 11, 2015
• 年：2015
• 卷：7
• 期：44
• 页码：24409-24418
• 全文大小：672K
• ISSN：1944-8252

文摘

(001)-Epitaxial La₂WO₆ (LWO) thin films are grown by pulsed laser deposition on (001)-oriented SrTiO₃ (STO) substrates. The 伪-phase (high-temperature phase in bulk) is successfully stabilized with an orthorhombic structure (a = 16.585(1) 脜, b = 5.717(2) 脜, c = 8.865(5) 脜). X-ray-diffraction pole-figure measurements suggest that crystallographic relationships between the film and substrate are [100]_LWO 鈭?[110]_STO, [010]_LWO 鈭?[11虆0]_STO and [001]_LWO 鈭?[001]_STO. From optical properties, investigated by spectroscopic ellipsometry, we extract a refractive-index value around 2 (at 500 nm) along with the presence of two absorption bands situated, respectively at 3.07 and 6.32 eV. Ferroelectricity is evidenced as well on macroscale (standard polarization measurements) as on nanoscale, calling for experiments based on piezo-response force-microscopy, and confirmed with in situ scanning-and-tunneling measurements performed with a transmission electron microscope. This work highlights the ferroelectric behavior, at room temperature, in high-temperature LWO phase when stabilized in thin film and opens the way to new functional oxide thin films dedicated to advanced electronic devices.