浓度梯度掺杂实现BiFeO3薄膜自极化

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中文摘要：BiFeO3 是一种非常有前途的无铅铁电材料，与大多数传统铁电材料相比，它具有更大的极化和更高的居里温度，为高温应用提供了可能。受到衬底强烈的夹持效应、较大的矫顽场和漏电流的影响，BiFeO3 薄膜难以被极化。自极化是解决这一问题的可行方法。本研究采用溶胶-凝胶法在Pt(111)/Ti/SiO2/Si衬底上生长了BiFeO3 薄膜，向上梯度薄膜(从衬底BiFeO3过渡到薄膜表面Bi0。80Ca0。20FeO2。90)以及向下梯度薄膜(从衬底Bi0。80Ca0。20FeO2。90过渡到薄膜表面BiFeO3)。通过细致地调控薄膜内部缺陷的定向分布形成内置电场，从而导致薄膜具有自极化特性。压电力显微镜结果表明:在BiFeO3 薄膜中，Ca的梯度方向可以调控自极化的方向。此外，类似二极管的单向导通特性验证了薄膜的自极化是由Ca的浓度梯度掺杂导致。X射线光电子能谱结果表明，氧空位的梯度分布导致的内置电场可能是造成自极化现象的原因。本研究为实现铁电薄膜的自极化提供了一种新的策略，并在以自极化的内置电场为驱动，提高光伏或光敏器件性能方面具有潜在的应用前景。

外文标题：Self-polarization Achieved by Compositionally Gradient Doping in BiFeO3 Thin Films

外文摘要：BiFeO3 is a highly promising lead-free ferroelectric material,surpassing most conventional ferroelectric materials in terms of the polarization and Curie temperature,offering a pathway for potential applications at elevated temperatures.Nevertheless,challenges arise due to strong clamping effect of substrate,large coercive fields,and high leakage currents,causing BiFeO3 films difficult to be polarized.The implementation of self-polarization presents a viable solution.Herein,we prepared BiFeO3,up-graded films(which transition from BiFeO3 to Bi0.80Ca0.20FeO2.90 from the substrate to the film surface),and down-graded films(which transition from Bi0.80Ca0.20FeO2.90 to BiFeO3 from the substrate to the film surface)using the Sol-Gel method on Pt(111)/Ti/SiO2/Si substrates.After directional distribution of defects within the film being carefully modulated,the BiFeO3 films are self-polarization when induced by build-in electric field.Piezoresponse force microscopy show that the up-graded and down-graded self-polarization behavior can be modulated by gradient direction of Ca in BiFeO3 thin films.Moreover,diode-like current-voltage signature verifies the composition gradient-induced self-polarization.The X-ray photoelectron spectroscopy results indicate that the polarization orientation mechanism may arise from the internal electric field attributed to the gradient distribution of oxygen vacancy.This work provides a new strategy to achieve self-polarization in ferroelectric thin films,as well potential novel application in improving the performance of photovoltaic or photosensitive devices as assisted by internal field via self-aligned ferroelectric polarization.

外文关键词：

self-polarizationgradient dopingbismuth ferrite filmSol-Gel method

作者：

戴乐、刘洋、高轩、王书豪、宋雅婷、唐明猛、DMITRY V Karpinsky、刘丽莎、汪尧进

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作者单位：

南京理工大学材料科学与工程学院,南京 210094

白俄罗斯国家科学院材料科学与应用研究中心,明斯克 220072,白俄罗斯

关键词：

自极化梯度掺杂铁酸铋薄膜溶胶-凝胶法

基金：

National Natural Science Foundation of ChinaNatural Science Foundation of Jiangsu Province,ChinaFundamental Research Funds for the Central UniversitiesYoung Elite Scientists Sponsorship Program by CAST(2021-2023QNRC001)

项目编号：

52102133BK2021035430921011217

出版年：

2024

DOI：

10.15541/jim20230278

无机材料学报

中国科学院上海硅酸盐研究所

无机材料学报

CSTPCD北大核心

影响因子：0.768

ISSN：1000-324X

年,卷(期)：2024.39(1)

参考文献量30