铁电氧化物薄膜光电转换机制及器件研究

Photoelectric effect based on ferroelectric polarization has a great potential application in the photovoltaic energy conversion devices and photoelectric detectors, and has been an emerging topic in the research field of light-matter interaction recently. At the present stage, two key scientific problems, the mechanism behind the photoelectric conversion process in the ferroelectric oxide films and the role of oxygen vacancies in the ferroelectric switchable photovoltaic effect, are still unclear. In this project, we will grow high-quality ferroelectric epitaxial films using laser molecular beam epitaxy (Laser-MBE) technique combined with high oxygen pressure reflection high-energy electron diffraction (RHEED). Then, we will focus on the intrinsic origin behind a high open-circuit voltage phenomenon in the ferroelectric photoelectric effect. Currently, there has been controversy on the role of oxygen vacancies in the ferroelectric switchable photovoltaic effect. To understand whether the oxygen vacancies play an important role in this process, we will realize the ferroelectric switchable photoelectric effect, and measure the content of oxygen vacancies by utilizing aberration-corrected scanning transmission electron microscopy with atomic resolution and sensitivity for light elements. Furthermore, the self-powered photoconductive ultraviolet detectors based ferroelectric oxide films will be investigated. It is hoped that the present project can provide the scientific basic for the future development of novel ferroelectric photoelectric energy conversion devices and ferroelectric photodetectors.

铁电极化相关的光电转换效应在光电能量转换和探测器件等领域拥有巨大的应用前景，近几年来逐渐成为光与物质相互作用学科前沿热点之一。现阶段，铁电氧化物薄膜光电转换的内在机制以及氧空位的作用尚不清晰，是当前亟待解决的关键科学问题。本项目将利用激光分子束外延生长技术，结合高氧压反射式高能电子衍射仪的原位实时监控功能，进行铁电氧化物薄膜的高质量层状外延生长，重点研究具有高输出电压的铁电光电效应的内在机制。针对氧空位在可反转铁电光电效应所起作用的争议，我们拟在铁电薄膜中实现可反转光伏效应，并利用球差校正扫描透射电镜能够直接观察到氧原子的优势，力求探究氧空位在该过程中所起的作用。在阐明以上关键科学问题的基础上，本项目将制备基于铁电材料的自供电光电导型紫外光电探测原型器件，为发展新型的铁电氧化物光电能量转换和探测器件提供科学基础。

铁电极化相关的光电转换效应在光电能量转换和探测器件等领域拥有巨大的应用前景，近几年来逐渐成为光与物质相互作用学科前沿热点之一。在本项目中，我们利用激光分子束外延技术生长系列铁酸铋、钛酸钡等铁电外延薄膜，实现了可翻转铁电光伏效应。并利用球差校正扫描透射电镜技术能够直接观测到氧原子的优势，揭示了氧空位迁移所起的重要作用。我们利用铁电光伏效应制备了新型的自供电紫外探测器，该铁电紫外探测器可以实现皮秒量级的超快光电响应。在以上研究基础上，我们制备了报道时开关比最高的铁电隧穿结，并通过控制超薄铁电畴的逐渐翻转实现了多态存储，进而成功模拟了突触功能。在项目执行期间，共在Advanced Materials、iScience、Advanced Functional Materials、Nano Energy、Physical Review B等高水平发表SCI论文33篇，其中第一/通讯作者文章16篇，申请发明专利7项，在国内外学术会议获得10余次邀请报告，完成了本项目的既定目标。