宏观应力应变对多结构微纳异质结光电量子效应的调控研究

The quantum tunneling and photoelectric effect of micro- and nano heterojunctions are hot and intensively investigated issues in material science，physics and electronics due to their importance in both fundamental research and device applications. However, very few researchers commit themselves to an in-depth investigation of the controllability of macroscopic stresses and strains on the quantum tunneling and photoelectric effect in micro-nano heterojunctions, especially those based on nanoscale functional materials. Such studies should be at a multiscale level with complicated factors such as surface, interface, and the size effects meticulously taken into account. In this project, focusing on a variety of functional nanoscale materials including nanoscale ferroelectrics, piezoelectrics, dielectrics, phase-transition materials and carbon materials, we will conduct a systematical investigation on controlling the quantum tunneling and the photoelectric effect in functional micro-nano heterojunctions by macroscopic stresses and strains. Basing on a thorough understanding of mechanical coupling features of the related electric and optical properties of these nanoscale functional materials, such as barrier thickness, polarization, internal electric field and electronic environment, it is potential to achieve regular control of the quantum tunneling and photoelectric effect by macroscopic stresses and strains. With the combination of multi-scale simulations and experimental investigation, this project is dedicated to explore and develop an efficient multi-scale researching method appropriate for the micro- and nano-heterojunctions under the effect of macroscopic stresses and strains, and aims to find the most optimal way to control the quantum tunneling and photoelectric effect. Our results should provide valuable information in designing and applications of electric and photoelectric devices, and should also lay a solid stone for related researches.

微纳异质结量子隧穿及光电效应，在基础研究和器件应用有着重要的意义。然而目前国内外甚少有研究针对基于功能纳尺度材料的微纳异质结，综合考虑表面、界面及尺寸效应等复杂条件，运用多尺度研究方法深入研究并系统总结量子隧穿和光电效应的宏观应力应变可控性。在本项目我们将针对纳尺度铁电、压电、介电、相变材料和碳纳米材料等多种功能纳尺度材料，对其构建的微纳异质结构的量子输运和光电效应调控进行系统研究。根据功能纳尺度材料的应力应变特性，通过宏观应力应变控制异质结势垒层厚度、极化、内电场及电子环境等，从而达到对微纳异质结量子隧穿和光电效应的调控。将重点结合多尺度模拟和实验制备分析，致力于探索和发展宏观应力应变下微纳异质结的多尺度研究方法，寻求量子隧穿及光电效应的最优调控方案，为微纳异质结在微纳光电子器件的设计应用提供重要参考，并为相关研究奠定坚实基础。

本项目围绕“宏观应力应变对多结构微纳异质结光电量子效应的调控研究”，针对压电、铁电、多铁、碳材料、金属绝缘相变材料、有机分子材料等一系列纳尺度功能材料，对宏观应力应变作用下微纳异质结基础特性、光电量子效应及可调控性，展开了系统、深入的理论和实验研究。理论方面，我们基于密度泛函理论、紧束缚近似、非平衡格林函数法、分子动力学、相场模拟和热力学建模等手段，并探索多方法相互配合的多尺度研究方法，对多种材料体系及其微纳异质结的基础特性和光电量子效应进行了理论预报，揭示了一系列微纳异质结基础特性和光电量子效应及其力学可调控性。例如，通过界面设计及利用尺寸效应，我们预报压电隧道结高达250倍的力控隧穿电阻变化；我们创新性提出引入缺陷能实现铁电隧道结性能提升--增强极化稳定性同时提高隧穿电导；我们设计构型可被力学控制的分子隧道结，可实现力可控的电阻-二极管-共振隧穿二极管一体的多功能电流微器件；针对石墨烯等二维材料力学稳定性、压电性及其电导力学调控性进行了细致研究，研究结果对于理解二维材料的存在性、二维材料压电性起源以及电导应变可调控性提供了理论依据；等等。实验上我们综合运用脉冲激光沉积、水热法、溶胶凝胶、电子束蒸镀、化学气相沉积配合模板、光刻技术、自组装等实验制备加工工艺制备了多种纳尺度功能材料及其异质结构，通过设计与整合发展出一套复杂力学荷载及复杂环境导致的复杂力学状态下功能材料微纳异质结多态特性测量新平台，对应力应变作用下微纳异质结基础特性和光电量子效应进行了大量的表征、测试，总结了大量的实验数据和规律。例如，实验首次揭示力学调控电阻开关效应；提出基于EuBiTe3的高灵敏宽带光电探测方案；利用界面设计和掺杂实现了钙钛矿太阳能电池高光电转化效率和低迟滞效应；等等。研究成果在力学、物理及材料学术期刊包括JMPS、Carbon、npjComput. Mater.、Sci. Rep.、Nanotechnology、Phys. Chem. Phys. Chem.、Appl. Phys. Lett.等国际重要期刊发表SCI论文55篇，另有一些成果待整理发表中。