双钙钛矿型氧化物薄膜电致阻变微观机理的研究

Resistance-change memory is characterized by simple structure, rapid writing speed, and high storage density. These characteristics make it one of the best nonvolatile memories with high application potential. In this project, we aim to investigate materials characteristics and device performance of resistance-change memories in double-perovskite oxides. Our overarching goals are 1) achieving fundamental understanding of the origin for the electric-field induced resistance-change at the microscopic scale and 2) realization of a prototype single resistor resistance-change memory device that takes advantage of the unique natural antisite defects in double-perovskite and voids sneak-path currents. The project is built upon our expertise in pulsed laser deposition for high quality double-perovskite thin films as well as magnetron sputtering, UV/E-beam lithography, and advanced microelectronic processing technologies available for us to make the prototype device. Films of La2Ni1+xMn1-xO6-d and those doped with alkaline earth metals at La site will investigated as single films or in tunnel junctions of micro- and nano-scale. The effects of the concentration of the oxygen vacancies on the characteristics of the resistance change will be systematically studied. The influence of active or noble electrode materials, which influenced different oxygen vacancy concentration, will also be investigated. We will focus on obtaining a precise correlation between the micro-structure of the materials/devices and their physical properties under different external electric field. These studies aim to reveal both the physical properties, which determines the characteristics of the oxide resistive memory, and the microscopic physical origin of the resistance change. Understanding the material's structural and electronic properties, advancing the preparation methods, and developing device processing technologies are the major expected outcomes of the project. Through these studies, basic research and device exploration on an important material system will be promoted and advanced. Such investigations will also lay scientific foundation for selecting materials and designing device structures for resistive memories.

阻性存储器具有结构简单、擦写速度快、存储密度高等特性，是最具有应用前景的非易失性存储器之一。 本项目将开展双钙钛矿型氧化物阻性存储特性的研究工作，利用双钙钛矿氧化物具有大量天然反位缺陷的结构特性，实现避免串生电流的单电阻型阻性存储器。利用激光脉冲沉积技术制备高质量的La2Ni1+xMn1-xO6-d及La位碱土金属掺杂的双钙钛矿型薄膜，利用磁控溅射技术、紫外光刻、电子束刻蚀技术及现代微电子加工技术制备微米及纳米级隧道结。系统研究不同氧空位含量、活性或惰性电极材料对氧化物阻变特性的影响，研究器件在外加电场作用下微结构与物理性质间的关联机制，揭示氧化物阻性存储器阻变特性的物理性基础，阐明氧化物电致阻变效应的微观机理，重点研究器件化过程中所涉及的材料结构、核心制备工艺与关键加工技术问题，以此推动该类材料体系的基础性研究和器件化应用探索，为阻性存储器件的实用化提供材料选择、结构设计等的科学依据。

电致阻变存储器具有制备简单、擦写速度快和存储密度高的优点，具有很强的应用前景。但是，电阻转变中材料自身结构和电阻转变性能的关系还不十分明确，这严重阻碍了器件的实际应用。本项目主要研究不同电极材料和氧空位含量对双钙钛矿氧化物薄膜阻变特性的影响。系统研究不同氧空位含量和电极材料对钙钛矿氧化物阻变特性的影响，研究器件在外加电场作用下微结构与物理性质间的关联机制，揭示氧化物阻性存储器阻变特性的物理性基础，阐明氧化物电致阻变效应的微观机理，为阻性存储器件的实用化提供材料选择、结构设计等的科学依据。.本项目圆满完成了上述研究内容，主要开展了双钙钛矿YFe0.5Cr0.5O3-d薄膜阻变存性质的研究，双钙钛矿La2NiMnO6-d薄膜阻变特性的研究，超薄钙钛矿铁电隧道结隧穿电阻效应的研究以及异质结界面状态对光电输运性质的影响等几个方面的研究工作。系统研究了氧空位含量、电极材料对氧化物阻变特性的影响，研究了器件微结构与物理性质间的关联机制，揭示了氧化物阻性存储器阻变特性均来源于氧空位在外加电场作用下形成的导电细丝通道，这为阻性存储器件的实用化提供研究基础。我们的研究发现，氧化物非晶薄膜样品具有制备简单且阻变的器件稳定性高等优点，这一方面可以避免复杂的多种制备工艺，另一方面可以克服多层膜间的晶格匹配问题，有利于提高器件的稳定性能，是一种很有应用前景的阻性器件。