表面等离激元增强应变BiFeO3外延薄膜异常光伏效应研究

项目名称： 表面等离激元增强应变BiFeO3外延薄膜异常光伏效应研究

项目编号： No.11274303

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 尹志岗

作者单位： 中国科学院半导体研究所

项目金额： 93万元

中文摘要： 铁酸铋的异常光伏效应是与其周期性条状畴密切相关的物理现象，具有可由外场开关、开路电压远大于带隙等独特性质，在光伏及未来光、电、力、弹多功能无源器件领域具有巨大的应用前景。然而，由于铁酸铋光谱响应范围较窄及内量子效率较低，造成光电转换效率不理想，严重制约了其可能应用。本项目将着眼于上述问题展开，探寻增强异常光伏效应的可行途径。首先，设计、制备应变铁酸铋外延薄膜，利用面内双轴压应力减小其带隙，从而拓宽其光谱吸收范围。其次，通过金属纳米颗粒表面等离激元陷光结构将光吸收限制在铁酸铋表面附近，充分利用表面处畴壁展宽使电荷阻挡作用得以增强的特点，有效抑制载流子复合，提高体系内量子效率。较单金属纳米颗粒而言，本项目利用胶束法制备的Ag/Au芯-壳结构纳米颗粒具有易于精确调控，可实现广谱吸收增强的优点。基于项目研究，探明表面等离激元增强应变铁酸铋薄膜异常光伏效应的微观机理，为其实用化奠定理论和实验基础。

中文关键词： 光伏效应；表面等离激元；铁酸铋；应变；带隙

英文摘要： Anomalous photovoltaic effect of BiFeO3 is an intriguing phenomenon cosely associated with its peroidic stripe-like ferroelectric domains, which is electrically switchable and can yield open-circuit voltage far above the bandgap.This effect bodes well for applications in photovoltaic areas and opens up the perspective of combining optical, electric, mechanical and magnetic functionalities in future generations of wireless devices. However, due to the rather narrow absorption spectrum and the low quantum efficiency of BiFeO3 system, the total energy conversion efficiency turns out to be very limited which restricts its possible applications. Here we will focus on the above problems and try to find out ways to enhance the anomalous photovoltaic effect of BiFeO3. On one hand, we plan to design and fabricate strained BiFeO3 epitaxial thin films. By imposing compressive biaxial-stress on the films the bandgap is reduced and therefore the absorption is extended. On the other hand，we propose to confine the absorption in the vicinity of the surface by using plasmonic light-trapping structures on purpose of increasing the internal quantum efficiency. The width of the domain walls are increased near the surface, which allows for better charge blocking across the wall and reduces the carrier recombination rate. Here we ch

英文关键词： Photovoltaic effect；Surface plasmon；Bismuth ferrite；Strain；Bandgap