Study on the Fabrication of Ferroelectric Ultrathin Films and Nanostructures by MOCVD and Their Size Effects

MOCVD铁电超薄膜和纳米结构的制备及其尺寸效应研究

• 批准号: 17360144
• 负责人: SHIMIZU Masaru
• 金额: $ 4.54万
• 依托单位: University of Hyogo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17360144/
• 关键词: Size Effect; PbTiO_3 Ultrathin Films; PbTiO_3 Nanoislands; MOCVD; Piezoresponse Force Microscopy; Critical Thickness; Phase Transition Temperature; Synchrotron X-Ray Diffraction; 強誘電体極薄膜; 強誘電体ナノ構造; 強誘電体; 極薄膜; ナノ構造; 自己集合化

In order to investigate the size effect in ferroelectric thin films and nanoisland structures, PbTiO_3 ultrathin films and nanosilands were fabricated by MOCVD and their structureal nature and ferroelectric properties were studied.1) Epitaxial PbTiO_3 ultrathin films with thicknesses of 10-0.9nm were successfully grown on SrRuO_3/SrTiO_3 by MOCVD.2) Piezoresponse measurements using Piezoresponse Force Microscopy (PFM) and observation of ferroelectric polarization using scanning nonlinear dielectric microscopy (SNDM) evidently proved the presence of ferroelectricity in PbTiO_3 ultrathin films with a thickness of 1.3nm (3 mono layers (ML)). Ferroelectrcity was not observed in the 0.9nm (2.2 ML) -thick film. In our experiment, critical thickness was 1.3nm.3) PbTiO_3 and PZT nanoislands were successfully fabricated on Pt/SrTiO_3 substrates by self-assembly using MOCVD. Three types of islands (pyramidal-shaped, triangular-prism-shaped and square-shaped islands) were grown on Pt/SrTiO_3(111), (110) and (001), respectively.4) PFM measurement proved the presence of ferroelectrcity in the PbTiO_3 nanoisland with a width of 27nm and a height of 1.2nm.5) Phase transition temperatures of PbTiO_3 nanoislands on Pt/SrTiO_3(111) and (110) were measured by Raman spectroscopy. From Raman measurement, it was fond that phase transition temperatures in pyramidal-shaped islands and triangular-prism-shaped islands decreased as island size decreased.6) Crystal structure of the nanosiland on Pt/SrTiO_3(111) was investigated using Synchrotron X-ray diffraction. As island size decreased, the c-axis lattice constant decreased at sizes smaller than 100nm though the a-axis lattice constant did not changed.7) Nano-sized Au dots were successfully fabricated by self-assembly. Using these Au nanodots as a top electrode, I-V characteristics of PbTiO_3 nanosilands on Pt/SrTiO_3 were measured.

为了研究铁电薄膜和纳米岛结构的尺寸效应，采用MOCVD法制备了PbTiO_3超薄膜和纳米岛，并研究了它们的结构性质和铁电性能。1)成功生长了厚度为10-0.9nm的外延PbTiO_3超薄膜。通过 MOCVD 在 SrRuO_3/SrTiO_3 上进行。2) 使用压电响应力显微镜进行压电响应测量（PFM）和使用扫描非线性介电显微镜（SNDM）的铁电极化观察明显证明了厚度为1.3nm（3个单层（ML））的PbTiO_3超薄膜中铁电性的存在。在0.9nm(2.2ML)厚的膜中没有观察到铁电性。在我们的实验中，临界厚度为1.3nm。3)利用MOCVD自组装技术在Pt/SrTiO_3基底上成功制备了PbTiO_3和PZT纳米岛。在Pt/SrTiO_3(111)、(110)和(001)上分别生长了三种类型的岛(金字塔形、三棱柱形和方形岛)。4)PFM测量证明了铁电体的存在。宽度为27nm、高度为1.2nm的PbTiO_3纳米岛。5)PbTiO_3纳米岛的相变温度通过拉曼光谱测量Pt/SrTiO_3(111)和(110)。拉曼测量发现，随着岛尺寸的减小，金字塔形岛和三棱柱形岛的相变温度也降低。6)利用同步辐射X射线研究了Pt/SrTiO_3(111)上纳米硅的晶体结构。衍射。随着岛尺寸的减小，尽管a轴晶格常数没有改变，但尺寸小于100nm时c轴晶格常数减小。7)通过自组装成功制备了纳米尺寸的Au点。使用这些 Au 纳米点作为顶部电极，测量了 Pt/SrTiO_3 上 PbTiO_3 纳米硅的 I-V 特性。

项目成果

Fabrication of Self-Assembled Au Nanodots and Their Applications to Ferroelectric Nanocapacitors

自组装金纳米点的制备及其在铁电纳米电容器中的应用

• 发表时间: 2006
• 期刊: Jpn. J. Appl. Phys. 45
• 作者: Eiji Higurashi;Yuichiro Tokuda;Masatake Akaike;and Tadatomo Suga;清水 勝;M.Shimizu;H.Fujisawa et al.;清水 勝;H.Fujisawa
• 通讯作者: H.Fujisawa

Microstructure and Ferroelectric Properties of Ultrathin PbTiO_3 Films by MOCVD

MOCVD超薄PbTiO_3薄膜的微观结构和铁电性能

• 发表时间: 2006
• 期刊: Materials Research Society Symposium Proceedings 902E
• 作者: H.Fujisawa et al.;H.Fujisawa et al.;H.Fujisawa et al.;清水 勝 他;Hironori Fujisawa
• 通讯作者: Hironori Fujisawa

Fabrication of Self-Assembled Au Nanodots and Their Applications to Ferrolelectric Nanocapacitors

自组装金纳米点的制备及其在铁电纳米电容器中的应用

• 发表时间: 2006
• 期刊: Jpn. J. Appl. Phys. 45
• 作者: Eiji Higurashi;Yuichiro Tokuda;Masatake Akaike;and Tadatomo Suga;清水 勝;M.Shimizu;H.Fujisawa et al.;清水 勝;H.Fujisawa;H.Fujisawa;H.Fujisawa;H.Fujisawa et al.
• 通讯作者: H.Fujisawa et al.

Fabrication of Ferroelectric Nanostructures and Their Properties

铁电纳米结构的制备及其性能

• 发表时间: 2007
• 期刊: Ceramics Japan 42
• 作者: Eiji Higurashi;Yuichiro Tokuda;Masatake Akaike;and Tadatomo Suga;清水 勝;M.Shimizu
• 通讯作者: M.Shimizu

Fabrication of Ir-based Electrodes by Metalorganic Chemical Vapor Deposition

金属有机化学气相沉积法制备铱基电极

• 发表时间: 2006
• 期刊: Jpn. J. Appl. Phys. 45
• 作者: Eiji Higurashi;Yuichiro Tokuda;Masatake Akaike;and Tadatomo Suga;清水 勝;M.Shimizu;H.Fujisawa et al.;清水 勝;H.Fujisawa;H.Fujisawa;H.Fujisawa;H.Fujisawa et al.;H.Fujisawa et al.
• 通讯作者: H.Fujisawa et al.