New electric functionality of lattice matched ferroelectric semiconductor heterostructures

晶格匹配铁电半导体异质结构的新电功能

基本信息

批准号：
08455014
负责人：
WATANABE Yukio
金额：
$ 3.9万
依托单位：
KYUSHU INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

1) Current transport through ferroelectric heterostructuresCurrent through (Pb, La)(Zr, Ti)0_3 ferroelectrics on perovskite semiconductors is found to exhibit diode characteristics of which polarity is universally deternuned by the carrier conduction type of the semiconductors. The observed current voltage (IV) characteristics, the polarity dependence, the relaxation, and the modulation are explicable, if we assume a pn or a pp junction at the ferroelectric semiconductor interface. A persisting highly reproducible resistance modulation by a dc voltage, which has a short retention, is observed and is ascribed to a band bending of the ferroelectric by the formation of charged states. A reproducible resistance modulation by a pulse voltage, which has a long retention, is observed in (Pb, La)(Zr, Ti)0_3/SrTiO_3 : Nb due to a possible band bending by the spontaneous polarization (P) switching. (p : hole conduction type, a : electron conduction type).Additionally, an anomalous increase of el … More ectric conduction with decreasing temperature was found in the current through Pb(Ti, Zr)0_3 ferroelectric/SrTiO_3 epitaxial heterostructures. Comparison with current-voltage characteristics of other ferroelectric epitaxial heterostructures and the analysis using the band diagram indicate that the current is tunneling through the Rn lunction formed by Pb(Ti, Zr)O_3 and SrTiO_3.Furthermore, properties of nm-scale electrical contact on single domained part of ferroelectric is investigated.2) Construction of theoretical frame workIdeal ferroelectrics have mostly been modeled as insulators, i.e., infinite band gap materials, having a spontaneous polarization. Based on this assumption, theories for the finite size effect, the domain configuration, and the depolarization field instability have been proposed. However, most of oxide perovskite ferroelectrics have finite band gaps of 3 to 4 eV.We show that the inclusion of the finite band gap effect changes drastically conventional understanding of the finite size effect, domain structares and others. The conclusions extracted from the present approach are consistent with recent experimental results. Less

1）通过铁电异质结构的电流传输发现电流通过钙钛矿半导体上的（Pb，La）（Zr，Ti）0_3铁电体表现出二极管特性，其极性通常由半导体的载流子传导类型决定。观察到的电流电压（IV）。如果我们假设铁电半导体上有 pn 或 pp 结，则特性、极性依赖性、弛豫和调制是可以解释的观察到由直流电压引起的持续的高度可再现的电阻调制，其具有短的保留时间，并且归因于通过带电状态的形成而导致的铁电体的能带弯曲。由于自发极化 (P) 切换（p：空穴）可能导致能带弯曲，因此在 (Pb, La)(Zr, Ti)0_3/SrTiO_3 : Nb 中观察到长保留。此外，通过与Pb(Ti,Zr)0_3铁电体/SrTiO_3外延异质结构的电流-电压特性比较，发现随着温度的降低，电导率异常增加。其他铁电外延异质结构和使用能带图的分析表明电流隧道通过由Pb(Ti, Zr)O_3和SrTiO_3。此外，研究了铁电体单畴部分纳米级电接触的性质。2)理论框架的构建理想的铁电体大多被建模为绝缘体，即无限带隙材料，基于这一假设，人们提出了有限尺寸效应、域结构和去极化场不稳定性的理论。氧化物钙钛矿铁电体具有 3 至 4 eV 的有限带隙。我们表明，有限带隙效应的包含改变了对有限尺寸效应、磁畴结构等的根本传统理解。从本方法中得出的结论与最近的结论是一致的。实验结果较少。