极化调控多铁BiFeO3异质结薄膜的电致阻变与光伏效应及其耦合研究

The discovery of ferroelectric resistive switching and photovoltaic effects in multiferroic BiFeO3(BFO) has expanded its physical connotation and potential application. Previous research showed that the ferroelectric polarization, which is intrinsic in BFO, plays important roles on both resistive switching and photovoltaic effects. It is of scientific importance and application potential to study the polarization modulated resistive switching and photovoltaic effects and their coupling in BFO. In this project, we intend to fabricate epitaxial BFO heterostructures on single crystal substrates by pulsed laser deposition and study their resistive switching, photovoltaic effects and their coupling. The effects of preparation parameters, heterostructure materials, microstructures, ferroelectric domains, space charge defects, and element doping on the film performance will be extensively explored. The relationships between ferroelectric polarization and resistive switching, and that between ferroelectric polarization and photovoltaic effects will be investigated, respectively. The ferroelectric polarization will be utilized to modulate the resistive switching and photovoltaic effects in BFO films. Moreover, studies will also be conducted on the interaction between the resistive switching and the photovoltaic effects, the light-modulated resistive switching and the resistance-modulated photovoltaic states, to explore the possible coupling among ferroelectric/resistive-switching/photovoltaic effects. Based on these studies, polarization modulated novel multilevel ferroelectric resistance memory and composite device with ferroelectric/resistive-switching/photovoltaic multi-functions might be developed.

多铁BiFeO3(BFO)材料的铁电电致阻变与光伏效应的发现拓展了该材料的物理内涵与应用领域，其内禀铁电极化在其电致阻变和光伏效应中具有重要的作用。研究铁电极化调控BFO的电致阻变和光伏效应及其耦合，具有重要的科学意义和应用前景。本项目拟采用脉冲激光沉积等技术在单晶基片上制备外延BFO异质结薄膜，研究其电致阻变、光伏特性及其耦合效应。研究制备条件以及异质结材料、界面微结构、铁电极化与畴状态、空间电荷缺陷、元素掺杂等对薄膜性能的影响；研究电致阻变、光伏性能与铁电极化的关系，利用极化调控异质结的电致阻变与光伏性能；研究薄膜的电致阻变与光伏效应的相互作用，研究阻变调控的光伏效应与光场调控的阻变特性，探索铁电/阻变/光伏之间的耦合作用与机理。在此基础上，探索研制极化调制的新型"多态存储"铁电电阻存储器与可能的新型铁电/阻变/光伏复合器件。

多铁BiFeO3(BFO)材料的电致阻变、磁性与光伏效应的发现拓展了该材料的物理内涵与应用领域。铁电极化是该材料的重要内禀特性。研究铁电极化调控BFO的电致阻变、磁性和光伏效应及其耦合，具有重要的科学意义和应用前景。本项目系统研究了利用PLD方法外延生长多铁BFO等金属氧化物的工艺条件。制备了多铁BFO、CFO、NFO、NiO等一系列金属氧化物异质结薄膜。全面测试和表征了这些薄膜的结构、形貌、外延织构、电致阻变、磁性和光伏效应，研究了制备条件与性能之间的对应关系。在多铁BFO及相关多铁功能薄膜异质结的电阻变换、光伏、磁性及其极化调控等多方面均取得了的预期的成果。观测到这些薄膜的优良的铁电、电致阻变、磁性及光伏性能。研究了这类薄膜异质结中电致阻变、磁性与光伏机理上的共性，揭示了这些薄膜的铁电、电致阻变、磁性及光伏性能的共存及内在耦合规律与机理，揭示了铁电极化对BFO类薄膜的电致阻变、磁性及光伏性能的有效调控及其机理。研究发现，薄膜异质结界面能级、界面势垒、氧空位及其相关载流子的状态与分布变化与这些薄膜异质结的电致阻变、磁性及光伏性能的调控密切相关。在Pt/BiFeO3/NSTO薄膜异质结中实现了铁电极化调控其电阻变换与磁性。在BEFO/NSTO薄膜异质结研究中发现，极化翻转可以对BEFO/NSTO界面处的势垒高度和耗尽区宽度进行调控，从而引起电阻开关特性。在Pt/BaTiO3/BiFeO3/TiO2/FTO异质结构中得到稳定的双极性阻变开关特性及光控阻态的变化，进而通过电-光效应对阻变开关的双调制实现了四个稳定的阻态。在CFO/NSTO薄膜异质结中观测到电阻变换与磁性的密切相关性以及氧空位在其调控中起到至关重要的作用。这些研究成果为多铁BFO系材料在新型磁电耦合、极化调控电阻变换、多场耦合多态存储器件领域可能的应用奠定了基础。可为可能的相关应用和市场开发提供前期技术支持。.在国际重要专业学术期刊上发表了SCI论文15篇，培养毕业了5名博士，2名硕士。