【作者】 周勇；

【导师】 唐东升；

【作者基本信息】 湖南师范大学 ， 凝聚态物理， 2013， 硕士

【摘要】 阻变存储器(或称忆阻器)由于兼容CMOS工艺、读写速度快、能耗低等特点有望成为新一代的存储器件。但是忆阻材料的忆阻机理目前尚不明确,这阻碍了阻变存储器的产业化,进一步研究忆阻效应,阐明其内在机理成为当务之急。现今,氧空位缺陷在氧化物的忆阻性能中的主要作用已经得到广泛认同。非化学计量比的WO3为研究氧空位迁移对忆阻效应的调控机制提供很好的平台。在此基础上,我们做了有关纳米离子学方面的研究。本文通过水热反应合成了WO3纳米线。通过调节PH值、温度、反应时间和硫酸钠用量获得了直径不同的纳米线。对纳米线进行了系列的表征,包括SEM、XRD等。利用光刻微加工工艺,构筑了基于单根三氧化钨纳米线的纳米器件。对纳米器件进行了电输运测试,并获得了以下结果：1、在电极和纳米线是欧姆接触的情况下,对纳米线进行了电化学掺杂。通过外加电场的作用,改变掺杂离子在纳米线内的轴向浓度分布,调控纳米线的电导。2、研究了水分子对纳米线忆阻性能的影响,进一步揭示纳米线的忆阻机制。研究发现,随着相对湿度的降低,纳米线的电输运回滞逐渐减少,纳米线的电导也会逐渐减少。3、在高湿度的情况下,我们发现纳米线的电导有明显的突变,由半导体型变为金属型。纳米线表面吸附的水分子,吸引纳米线中的自由电子。在纳米线和金电极接触界面感应出带正电荷的氧空位。使原本为肖特基接触的界面转变为欧姆接触的界面。在欧姆接触的情况下,纳米线的电导随着相对湿度的增加而降低。更多还原

【Abstract】 Resistive random access memory (RRAM or Memristors) has been considered as next-generation nonvolatile memory due to its compatibility with CMOS process, fast read/write speed and low power consumption. However, the memristive mechanism of the material is still under debate, which hinders the industrialization of RRAM. Research on memristive mechanism becomes the top priority. Recently, oxygen vacancies in oxide which play the main role in the RRAM have been widely accepted. Non-stoichiometric WO3is more favorable energetically than stoichiometric WO3under atmospheric conditions, which implies that WO3is intrinsically’ self-doped’ by native oxygen vacancy point defects. We studied nanoionics based on WO3nanowires.WO3nanowires have been successfully synthesized by a simple hydrothermal method. We made a series of characterization of the nanowires, including SEM, XRD, etc. The nano-device based on individual tungsten trioxide nanowire was fabricated by conventional photolithography procedure. The achievements are shown as follows:1. In nano-device, a single tungsten trioxide nanowire was used as working electrode, and electrical transport of the single nanowire was recorded in situ to detect the evolution of the nanowire after Li+ion intercalation. Positively charged Li+ions prefer to drift when the electric field is strong enough, the axial distribution of Li+and then the electrical transport properties can be more easily modulated by bias voltage.2. We furthermore investigate the effect of vapor on resistive switching of WO3nanowire device to explore the memristive mechanism. The conductance and hysteresis loop of the nanowire reduced as a result of relative humidity reduced.3. Under high humidity, we found that the conductance of the nanowire has big change. Water molecules attract free electrons in the nanowire after being adsorbed on it, which induced the oxygen vacancies at the contact interface, as a result, the contact changed from schottky to ohmic.更多还原