硅上脉冲激光沉积外延无铅钙钛矿氧化物薄膜及其铁电和电光特性的研究

The epitaxial growth of lead-free perovskite oxides BaTiO3 (BTO) and BiFeO3 (BFO) with good non-linear optic properties onto Si wafers, has significant potential applications for the realization of Si-based integrated green electro-optic devices with the low power consumption and the high speed. However, great challenges exist for the epitaxy of the oxide films on Si, such as the interface and the crystallization controls. Furthermore, the correlation between the structural properties and electronic and optical properties of the nanoscale oxide thin films have not been thoroughly understood. This project aims to realize firstly the single crystalline Y-stabilized ZrO2 and SrTiO3 buffer layers on Si with abrupt interfaces, based on which, to epitaxially grow BTO an BFO thin films on Si by employing pulsed laser deposition (PLD). Then the impacts of buffer layers, growth parameters (the temperature, the oxygen partial pressure and the annealing etc.), substrate orientations and the strain on the ferroelectric thin films will be systematically studied. The correlation between the structural properties of the oxides and their dielectric, ferroelectric and electro-optic properties will be explored. Through the tailoring and optimization of the film properties, one could eventually obtain BFO and BTO films on Si with high quality electro-optic properties. The project will not only completely utilize the PLD method with features like the easy manipulation and maintenance and the low cost to epitaxially grow oxides on Si, but also will carry out detailed research on the related material, physics and chemistry issues. It will provide a solid base for the future related device applications.

将具有良好非线性光学性质的无铅钙钛矿铁电钛酸钡（BaTiO3，BTO）和铁酸铋(BiFeO3，BFO) 氧化物的纳米薄膜外延生长在硅基板上，对于实现绿色、低能耗和高速的硅基集成光学器件有着重大意义。然而，硅上外延生长氧化物薄膜面临着界面和结晶控制等诸多困难，而且人们对于BTO和BFO薄膜的结构特性与其电、光特性的关联也缺乏透彻的理解。本课题旨在利用脉冲激光沉积的方法，在硅上实现界面锐利的单晶Y-ZrO2或SrTiO3 缓冲层,并以此为基础在硅上外延生长BTO和BFO纳米薄膜，进而系统地研究缓冲层、生长参数、基板取向和应变对于铁电薄膜的影响，探讨薄膜结构特性与其介电、铁电和电光特性的关联，从而对它们进行调控和优化，最终得到硅上具有高质量电光特性的无铅铁电薄膜。课题不但完全利用脉冲激光沉积方法在硅上外延氧化物，并且对其中材料、物理和化学等相关问题进行深入探讨，从而对未来器件应用提供坚实基础。

将具有良好电学和光学性质的钛酸钡（BTO）等无铅介电和铁电氧化物的纳米薄膜外延生长在硅（或锗）半导体基板上，对于实现绿色、低能耗和高速的后摩尔功能器件有着重大意义。然而，硅（或锗）上外延生长氧化物薄膜面临着界面和结晶控制等诸多困难，而且人们对于钛酸钡等无铅薄膜的结构特性与其电、光特性的关联也缺乏透彻的理解。本项目利用脉冲激光沉积的方法，在硅上实现界面锐利的单晶Y-ZrO2或SrTiO3缓冲层,并以此为基础在硅（或锗）上外延生长无铅氧化物纳米薄膜，进而系统地研究缓冲层、生长参数、掺杂和应变对于钛酸钡、铌酸钾钠、钛酸铋钠和氧化铪等无铅薄膜的影响，探讨薄膜结构特性与其介电、铁电和光特性的关联,从而对它们进行调控和优化，最终得到硅上具有高质量功能特性的无铅薄膜。项目还探索并实现了钛酸钡直接在锗衬底上的外延生长（无需缓冲层）、石墨烯缓冲层的影响、氧化铪薄膜的宽频谱光发射和性能优良的固态发光器件。本项目对在硅（或锗）半导体基板上外延生长氧化物这一主题下的材料、物理和化学等相关问题进行深入探讨，从而对未来器件应用提供坚实基础。