Zhang Zimeng, Hsu Shang-Lin, Stoica Vladimir A, Paik Hanjong, Parsonnet Eric, Qualls Alexander, Wang Jianjun, Xie Liang, Kumari Mukesh, Das Sujit, Leng Zhinan, McBriarty Martin, Proksch Roger, Gruverman Alexei, Schlom Darrell G, Chen Long-Qing, Salahuddin Sayeef, Martin Lane W, Ramesh Ramamoorthy
Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
Adv Mater. 2021 Mar;33(10):e2006089. doi: 10.1002/adma.202006089. Epub 2021 Feb 2.
The synthesis of fully epitaxial ferroelectric Hf Zr O (HZO) thin films through the use of a conducting pyrochlore oxide electrode that acts as a structural and chemical template is reported. Such pyrochlores, exemplified by Pb Ir O (PIO) and Bi Ru O (BRO), exhibit metallic conductivity with room-temperature resistivity of <1 mΩ cm and are closely lattice matched to yttria-stabilized zirconia substrates as well as the HZO layers grown on top of them. Evidence for epitaxy and domain formation is established with X-ray diffraction and scanning transmission electron microscopy, which show that the c-axis of the HZO film is normal to the substrate surface. The emergence of the non-polar-monoclinic phase from the polar-orthorhombic phase is observed when the HZO film thickness is ≥≈30 nm. Thermodynamic analyses reveal the role of epitaxial strain and surface energy in stabilizing the polar phase as well as its coexistence with the non-polar-monoclinic phase as a function of film thickness.
据报道，通过使用充当结构和化学模板的导电焦绿石氧化物电极，可合成完全外延的铁电铪锆氧化物（HZO）薄膜。以铅铱氧化物（PIO）和铋钌氧化物（BRO）为代表的此类焦绿石具有金属导电性，室温电阻率小于1mΩ·cm，并且与氧化钇稳定的氧化锆衬底以及生长在其顶部的HZO层晶格紧密匹配。利用X射线衍射和扫描透射电子显微镜确定了外延和畴形成的证据，结果表明HZO薄膜的c轴垂直于衬底表面。当HZO薄膜厚度≥约30nm时，观察到从极性正交相出现非极性单斜相。热力学分析揭示了外延应变和表面能在稳定极性相以及作为薄膜厚度函数的非极性单斜相共存中的作用。
