Size Effect in Ferroelectric Thin Films Prepared by Atomic Layr Controlled Growth

原子层控制生长铁电薄膜的尺寸效应

基本信息

批准号：
07650367
负责人：
ISHIKAWA Kenji
金额：
$ 1.28万
依托单位：
Shizuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650367/
关键词：
ferroelectrics thin film size effect laser ablation atomic layr control BaTiO_3 PbTiO_3 PZT レーザ・アブレーション

项目摘要

The dielectric properties, such as the Curie temperature, dielectric constant, coercive field and others, depend on the film thickness or the diameter of the constituent crystallites when the size reduces to sub-micron order. The purpose of this study is to clarify the origin of the size effects. Thin films of several tens to several hundreds nanometer in thickness of lead titanate and PZT were grown on silicon substrates by means of laser ablation and sol-gel technique. A platinum-coated silicon was mainly used as a substrate. Pellets of BaTiO_3 (BT), PbTiO_3 and PZT ceramics were used as the target material of the laser ablation growth.The surface of the film was investigated by a scanning electron microscope and an atomic force microscope and found to be flat with nanometer scale. The Curie temperature of very thin BT film was slightly higher than that of bulk crystal. This tendency was opposite to our expectation, the Curie temperature would shift towards low temperatures. The results show that the inner stress plays an important role in size effects. Thin films of PT grown by laser ablation was investigated by X-ray diffraction and found to be well crystallized. Film of PZT was grown on the PT layr by a sol-gel method. The film showed a large peak around 350ﾟC, very close to the Curie temperature of bulk PZT.This means the presence of PT layr is effective to proceed the crystallization of PZT film layr.Experiments on the atomic layr growth was performed in a compound semiconductor system since it was difficult to make layr by layr growth of dielectric crystals.

当尺寸减小到亚微米级时，介电性能（例如居里温度、介电常数、矫顽场等）取决于薄膜厚度或组成微晶的直径。这项研究的目的是澄清其起源。通过激光烧蚀和溶胶-凝胶技术在硅衬底上生长几十到几百纳米厚的钛酸铅和PZT薄膜。采用BaTiO_3(BT)、PbTiO_3和PZT陶瓷颗粒作为激光烧蚀生长的靶材。通过扫描电子显微镜和原子力显微镜观察薄膜表面，发现薄膜表面平整。非常薄的BT薄膜的居里温度略高于块状晶体的居里温度，这一趋势与我们的预期相反，居里温度会向低温方向移动。结果表明，内应力起着重要作用。通过X射线衍射研究了激光烧蚀生长的PT薄膜的尺寸效应，发现通过溶胶-凝胶方法在PT层上生长了良好的PZT薄膜。 350℃，非常接近块体PZT的居里温度。这意味着PT层的存在可以有效地进行PZT薄膜层的结晶。原子实验由于难以通过介电晶体的层生长来形成层，所以在化合物半导体系统中进行层生长。