忆阻器单元电学特性计算模拟研究

发布时间：2019-01-05 03:28

【摘要】：目前,当COMS器件面临集成工艺技术尺寸限制,忆阻器作为一种新型的纳米级存储器件受到了众多学者的关注。低功耗、高速度、高集成度、兼具信息存储与计算功能的忆阻器,为信息存储和超高性能计算带来了前所未有的机遇。它作为下一代非易失性存储器中的佼佼者,有望替代如今主流的闪存器件。忆阻器材料相关物理机制存在很大分歧,忆阻机制不清晰,忆阻性能缺乏有效的调控方法,这些原因限制了忆阻器性能提高和实用进程。虽然目前已有大量实验研究忆阻器的忆阻特性,并给出了一定的理论模型,但是由于纳米尺度下器件内部电子运输表征手段匮乏,导致其具体的微观过程至今仍没有一个清晰的认识,许多地方还存在争议。因此,从理论计算模拟的角度出发,开展忆阻器电学基本特性研究,弄清楚忆阻器的阻变机制仍是目前的研究重点。忆阻单元电学特性计算模拟研究将为材料研究和提升忆阻特性奠定理论基础。第一性原理计算方法已经在材料研究领域得到了广泛的应用,它可以从微观层面去研究材料的物理特性,更重要的是它一种可行的预测材料的电学特性的有效方法。该方法能够模拟计算纳米级器件的结构、缺陷、掺杂等特性,并从电子层面分析计算模拟结果,利用计算结果对纳米器件的电学特性进行预测。因此采用第一性原理计算研究忆阻器单元的电学特性,从而分析其忆阻机制是一个理想的选择。本文对忆阻单元材料的阻变机理进行了一个详细的合理推测,并提出了带电荷的空位缺陷随外加电场发生迁移是导致其发生阻变行为的主要原因。用计算软件Atomistix Tool Kit对忆阻单元进行了掺杂空位缺陷的模型建立。基于物理模型分析,对不同电压下忆阻单元功能层中的空位缺陷位置进行了预测,建立了遵循边界迁移模型的一系列的双电极单元器件模型。通过对器件的直流I-V特性进行计算分析,对其阻变行为进行了合理的解释,结果表明边界迁移的确会使器件电阻发生变化。对今后实验以及工艺制备提供了理论参考,也为分析忆阻器件的忆阻机理提供了理论依据。
[Abstract]:At present, when the COMS device faces the size limitation of integrated technology, the memory device as a new type of nano-level memory device has attracted many scholars' attention. Low power consumption, high speed, high integration, and information storage and computing functions of the resistor, for information storage and ultra-high performance computing has brought unprecedented opportunities. As a leader in the next generation of non-volatile memory, it is expected to replace the current mainstream flash memory devices. The material related physical mechanism of the resistor is very different, the mechanism of the memory is not clear, and the performance of the memory is short of effective control methods. These reasons limit the performance improvement and the practical process of the resistive device. Although a large number of experiments have been carried out to study the memory characteristics of the device, and a certain theoretical model has been given, the internal electronic transport characterization of the device is scarce at nanometer scale. So far, there is still not a clear understanding of its specific micro-process, and there are still disputes in many places. Therefore, from the point of view of theoretical calculation and simulation, it is still the focus of current research to study the basic electrical characteristics of the resistive device and to find out the resistive mechanism of the resistive device. The simulation study of electrical characteristics of memory units will lay a theoretical foundation for the study of materials and the enhancement of memory characteristics. First-principles calculation method has been widely used in the field of material research. It can study the physical properties of materials from the microscopic level and, more importantly, it is an effective method to predict the electrical properties of materials. This method can simulate and calculate the structure, defect and doping characteristics of nanoscale devices, and analyze the simulation results from the electronic level, and predict the electrical properties of nanodevices by using the calculated results. Therefore, it is an ideal choice to study the electrical characteristics of the resistive unit by first principle calculation and to analyze the mechanism of the resistor. In this paper, the resistance mechanism of the memory element material is inferred in detail, and it is suggested that the migration of the charged vacancy defect with the applied electric field is the main cause of the resistance behavior. The model of doped vacancy defect of the memory unit was established by using the calculation software Atomistix Tool Kit. Based on the physical model analysis, the vacancy defect location in the functional layer of the memory cell at different voltages is predicted, and a series of two-electrode single-component models following the boundary migration model are established. Through the calculation and analysis of the DC I-V characteristics of the device, the resistive behavior of the device is explained reasonably. The results show that the boundary migration does change the resistance of the device. It provides a theoretical reference for future experiments and fabrication, and also provides a theoretical basis for the analysis of the mechanism of the device.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM501

【相似文献】