项目名称： 外电场作用下PZT铁电体调控LAO/STO氧化物异质界面二维电子气的高分辨原位电子全息研究

项目编号： No.11504162

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 王双宝

作者单位： 广西大学

项目金额： 21万元

中文摘要： 将功能化薄膜与氧化物二维电子气相结合，在外场作用下实现导电性能的可调控性，是发展新型电子元器件的重要方法。目前对钙钛矿型Pb(Zr,Ti)O3/LaAlO3/SrTiO3异质结构中二维电子气产生和外场调控的机理还有待深入研究。精确地获得外场作用下异质界面的原子和电子精细结构以及界面电荷电势的变化信息是理解其中物理机制的前提。因此，有必要对异质界面的结构和电子特性进行高分辨率原位透射电镜的表征和分析。本课题拟以原子分辨率的原位电子全息术为基础，结合双球差透射电镜中的亚埃分辨率原子成像技术、亚电子伏特分辨率电子能量损失谱深入研究PZT/LAO/STO异质结界面的原子占位、晶格畸变、化学价态、电荷电势分布及其在外加电场作用下的演变，旨在阐明影响LAO/STO界面二维电子气导电的根本原因及其外电场作用下PZT铁电体覆层调控二维电子气的机理,为新型信息存储器件的研究和开发提供理论指导。

中文关键词： 氧化物异质结；二维电子气；界面结构；电子全息术；原位表征

英文摘要： Integrate oxide two-dimensional electron gas (2DEG) with additional functional layers and then realize the external signal modulating 2DEG is a critical method for high performance devices development. Now the formation and modulation mechanism of 2DEG in perovskite Pb(Zr,Ti)O3/LaAlO3/SrTiO3 heterostructures need to be researched in depth. Obtaining the accurate changing information of atomic and electronic structure as well as charge distribution at the epitaxial PZT/LAO/STO heteroinerface under applied external electric field is a prerequisite for the understanding of physical mechanism behind them. Therefore, it is necessary to conduct the ultra high resolution characterization and analysis of heterointerface by in-situ transmission electron microscope (TEM). In this proposal, we will employ in-situ electron holography at atomic scale combined with sub-Ångström spatial resolution imaging techniques, sub-eV energy resolution electron energy loss spectrum (EELS) to study atomic occupation, lattice distortion, chemical valence state, charge distribution at the interfaces of PZT/LAO/STO heterostructures as well as their corresponding evolution under applied external electric field based on a double aberration-corrected S/TEM. The goal of this research is to clarify the intrinsic factors that influence the 2DEG at LAO/STO interface and reveal the modulation mechanism of 2DEG conductivity for polar/nonpolar ferroelectric PZT overlayer. The proposed experimental study will provide the useful theoretical guide for the development of novel non-volatile memory nanoelectronics.

英文关键词： oxide heterostructure;two-dimensional electron gas;interfacial structure;electron holography;in-situ characterization