Coherent Epitaxy of a Ferroelectric Heterostructure on a Trilayered Buffer for Integration into Silicon
Coherent Epitaxy of a Ferroelectric Heterostructure on a Trilayered Buffer for Integration into Silicon
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用于集成到硅中的三层缓冲器上铁电异质结构的相干外延
DOI：
10.1002/aelm.201500334
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发表时间：
2016
影响因子：
6.2
通讯作者：
A. Sawa
中科院分区：
文献类型：
--
作者：
H. Yamada;Y. Toyosaki;A. Sawa
DOI：10.1002/aelm. 201500334 Si上的薄膜。[3，10]通过使用氧化物单层或双层缓冲层，已经改进了Si上铁电MIM结的制造。[12-15] Scigaj et al. [14]在LaNiO 3/CeO 2/YSZ/Si异质结构上制备了超平的BaTiO 3（BTO）薄膜，并获得了6-10 µC cm-2的大铁电回复极化（Pr）。Li等人[15]利用原子力显微镜的导电针尖作为上电极，观察了（La，Sr）MnO 3（LSMO）/SrTiO 3（STO）/Si异质结上外延BTO层中的TER.这一结果证明了在Si上构建基于TER的NVM的可行性，但是在铁电MIM结构中尚未实现TER效应。为了观察MIM结构中的TER效应，铁电薄膜需要在整个上电极区域具有平坦的表面和均匀的厚度.本文采用STO/SrO 1+ δ/YSZ氧化物三层缓冲层，在Si衬底上制备了具有大Pr和TER效应的铁电MIM结.扫描透射电子显微镜（STEM）实验证实，在STO和YSZ层之间插入SrO 1+ δ层后，STO层的结晶度比YSZ层有了明显的提高，而且与STO形成了清晰而均匀的界面。结果，BTO层和LSMO底部电极在三层缓冲层上外延生长，保持了高结晶度和原子级平坦界面。我们在缓冲Si上的Co/BTO/LSMO FTJ中实现了非易失性电阻。
DOI: 10.1002/aelm. 201500334 films on Si.[3, 10] The fabrication of ferroelectric MIM junctions on Si has been improved by the use of oxide single-or double-layer buffers.[12–15] Scigaj et al.[14] fabricated ultraflat films of BaTiO 3 (BTO) on LaNiO 3/CeO 2/yttria-stabilized ZrO 2 (YSZ)/Si heterostructures, and they achieved a large ferroelectric remanent polarization (Pr) of 6–10 µC cm–2. Li et al.[15] observed TER in an epitaxial BTO layer on a (La, Sr) MnO 3 (LSMO)/SrTiO 3 (STO)/Si heterostructure by using a conductive tip of atomic-force microscope as a top electrode. This result demonstrated the feasibility of constructing TER-based NVMs on Si, but the TER effect has not yet been achieved in a ferroelectric MIM structure. To observe the TER effect in an MIM structure, a ferroelectric film needs to have flat surface and a uniform thickness over the entire area of the top electrode.In the present study, by using an STO/SrO 1+ δ/YSZ oxide trilayered buffer, we fabricated ferroelectric MIM junctions that showed a large Pr and a TER effect on a Si substrate. Scanning transmission electron microscope (STEM) experiments confirmed that the insertion of a SrO 1+ δ layer between the STO and YSZ layers produced a marked improvement in the crystallinity of the STO layer compared with that of the YSZ layer and, moreover, produced a sharp and uniform interface with the STO. As a result, the BTO layer and the LSMO bottom electrode grew epitaxially on the trilayered buffer, maintaining a high crystallinity and an atomically flat interface. We realized nonvolatile electroresistance in Co/BTO/LSMO FTJs on the buffered Si.