权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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.

介电性能，如居里温度、介电常数、矫顽力场等，取决于薄膜厚度或组成晶的直径，当尺寸减小到亚微米级时。本研究的目的是澄清大小效应的起源。采用激光烧蚀和溶胶-凝胶技术在硅衬底上制备了数十~数百纳米厚度的钛酸铅和PZT薄膜。镀铂硅主要用作衬底。采用BaTiO_3 （BT）、PbTiO_3和PZT陶瓷球团作为激光烧蚀生长的靶材。用扫描电子显微镜和原子力显微镜对薄膜表面进行了研究，发现薄膜表面呈纳米级平面。超薄BT薄膜的居里温度略高于体晶。这一趋势与我们的预期相反，居里温度会向低温转移。结果表明，内应力在尺寸效应中起重要作用。用x射线衍射对激光烧蚀生长的PT薄膜进行了研究，发现其结晶良好。采用溶胶-凝胶法在PT层上生长PZT薄膜。薄膜在350℃左右出现一个峰值，非常接近大块PZT的居里温度。这说明PT层的存在有利于PZT膜层的结晶。由于介电晶体难以逐层生长，因此在化合物半导体系统中进行了原子层生长实验。