基于纳米尺寸的分子电子信息存储研究

以有机分子为基础的"纳米存储"是一种新型的数据存储系统,具有替代目前广泛应用的半导体存储器件的趋势。目前,有两种"分子"被潜在地应用于"纳米存储",一种是分子电子器件,包括分子导线、分子整流器、分子开关以及分子晶体管;另外一种应用了纳米结构的材料,如纳米管、纳米导线以及纳米粒子等。本文以分子电子器件的制备和构筑单元的设计为视角,根据分子结构、装置类型、终端电极的数目以及分子介质的状态对分子电子器件进行了分类,同时也对分子结的制备、特征、电荷转移机制以及三终端分子器件、树状化合物分子尺寸纳米电荷存储的发展进行了探讨,并对纳米信息存储存在的问题及发展方向进行了展望。     

纳米电子器件

概述了用于超高密度集成电子计算机的纳米尺寸电子开关器件的研究进展。讨论了场效应晶体管的两类替代物： （１） 量子效应和单电子固态器件, （２） 分子电子器件。提出了每一类器件的分类方法, 描述了其工作原理并对各种器件进行了比较     

分子电子学的研究目标和途径

本文阐明了继真空器件和半导体器件之后,分子电子器件作为第三代器件将呈现于信息科学之中。这不仅是器件发展趋势所致,也是基于进化求解原理的新一代计算系统发展的需要。文中提出了用分子电子器件构成的关联存贮器和网络模型;并讨论了近期的研究目标与途径。     

分子尺寸器件与单分子器件

未来的计算机可以小到什么程度?迄今无人可以做详尽的回答。但毫无疑问,硅基集成电路由于光刻技术的限制和生产成本随尺寸变小作指数增长,将很快达到它的极限(最小线宽100nm)。目前国际上已提出未来的纳米电子器件的各种方案,其中最小的器件有可能由单个分子所构成。扼要讨论了当前最“热门”的分子尺寸电子器件以及将要进一步发展的单分子电子器件。其中具有电双稳性能的分子是最可期许的材料。初步的研究结果表明能得到构成逻辑门用的单分子开关、超高密度存贮器和单分子整流器等功能器件的原型。最后还讨论了分子电子学进一步发展的前景和问题。     

纳米间隙电极的制备及应用

综述了国内外纳米间隙电极的制备方法,其中主要包括扫描隧道显微镜法、Hg滴法、机械断裂法、微加工法、电迁移法、电化学法等,对每种方法的制备过程及原理进行了较详细的介绍;对每种纳米间隙电极在分子电子学方面的应用,特别是对利用纳米间隙电极测定单分子的I-V性质、制作分子整流器和分子晶体管等工作做了简单介绍。突出了纳米间隙电极在分子器件研究中的重要作用;最后讨论了分子电子学所面临的一些问题并对该领域的发展方向作出了展望。     

固体纳米电子器件和分子器件

综述了两类纳米电子器件———固体纳米电子器件和分子电子器件的定义、分类方法及特点,并提出发展纳米电子器件的几点建议。     

石墨烯纳米间隙电极对的制备研究进展

石墨烯的高晶体质量、高电导率、单层结构以及与有机半导体的良好兼容性使其成为纳米器件和分子器件的理想电极材料,纳米间隙电极对是构筑纳米器件的基础,发展了两种制备石墨烯纳米间隙电极对的方法——纳米线和金丝交替掩膜法以及原子力针尖裁剪法,其过程简单,制备的石墨烯间隙为100～200 nm.石墨烯纳米间隙电极对是制备纳米器件、...     

纳米电子器件

概述了用于超高密度集成电子计算机的纳米尺寸电子开关器件的研究进展。讨论了场效应晶体管的两类替代物：（１）量子效应的单电子固态器件；（２）分子电子器件。提出了每一类器件的分类方法，描述了其在工作原理并对各种器件进行了比较。     

量子电子器件及其应用

随着半导体芯片的特征尺寸从微米量级向纳米量级挺进,半导体的量子效应现象显现。文章阐述了半导体器件中的量子尺寸效应、隧道效应、干涉效应等量子效应的种类以及利用这些量子效应制作的量子点器件、谐振隧穿器件和单电子器件三大种类量子电子器件。介绍了各类量子电子器件的原理以及它们具有超高速、超高频、高集成度、低功耗和高特征温度等优越特性,并着重介绍了各类量子电子器件的制造方法。在此基础上,指出了量子电子器件的应用及发展前景。     

纳米加工和纳米电子器件

介绍了电子束曝光技术、EUV光刻技术和X射线光刻技术的进展;对各种纳米电子器件如单电子器件、共振隧穿器件和分子电子器件的研究现状及面临的主要挑战进行了讨论。     

Reversible Switching Phenomenon in Diarylethene Molecular Devices with Reduced Graphene Oxide Electrodes on Flexible Substrates

Photoswitching molecular electronic devices with reduced graphene oxide (rGO) top electrodes on flexible substrates are fabricated and characterized. It has been reported previously that diarylethene molecular devices with poly‐(3,4‐ethylenedioxythiophene) stabilized with poly‐(4‐styrenesulfonic acid)/Au top electrodes can hold two stable electrical conductance states when the devices are exposed to UV or visible light during device fabrication. However, those devices fail to show the reversible switching phenomenon in response to illumination after device fabrication. By employing conducting and transparent rGO top electrodes, it is demonstrated that the diarylethene molecular devices show a reversible switching phenomenon, i.e., the fabricated devices change their conductance state in response to the alternating illumination with UV and visible light. Furthermore, the molecular devices with rGO top electrodes also exhibit good longtime stability and reliable electrical characteristics when subjected to various mechanical stresses (bending radius down to 5 mm and bending cycle over 10⁴).     

单次可编程金属-分子-金属器件

提出了一种单次可编程的金属-分子-金属器件.该器件利用一种经过改良的Rotaxane LB膜作为功能层.可以和应用于场编程门阵列电路中的无机反熔丝器件相比拟,将在有机可编程电路和容错电路等方面有较广泛的应用.所有的加工工艺都是低温工艺,使得该器件可以和其他有机器件集成.电学测试表明该器件有良好的单次编程能力,其击穿电压为2.2V,关态电阻为15kΩ,而开态电阻为54Ω.据分析,这一特性是由非对称的电极结构和金属原子在高电场作用下穿透了分子薄膜所造成的.     

The metal/organic monolayer interface in molecular electronic devices

The metal/molecules/metal is the basic device used to measure the electronic properties of organic molecules envisioned as the key components in molecular-scale devices (molecular diode, molecular wire, molecular memory, etc.). This review paper describes the main techniques used to fabricate a metal/molecules/metal device (or more generally electrode/molecules/electrode junctions, with electrodes made of metal or semiconductor). We discuss several problems encountered for the metallization of organic monolayers. The organic/electrode interface plays a strong role in the electronic properties of these molecular devices. We review some results on the relationships between the nature of the electrode/molecule interface (physisorbed or chemisorbed, evaporated metal electrode, mechanical contact, etc.) and the electronic transport properties of these molecular-scale devices. We also discuss the effects of symmetric versus asymmetric coupling of the two ends of the molecules with the electrodes.     

Redox‐Induced Asymmetric Electrical Characteristics of Ferrocene‐Alkanethiolate Molecular Devices on Rigid and Flexible Substrates

The electrical properties of ferrocene‐alkanethiolate self‐assembled monolayers (SAMs) on a high yield solid‐state device structure are investigated. The devices are fabricated using a conductive polymer interlayer between the top electrode and the SAM on both silicon‐based rigid substrates and plastic‐based flexible substrates. Asymmetric electrical transport characteristics that originate from the ferrocene moieties are observed. In particular, a distinctive temperature dependence of the current (i.e., a decrease in current density as temperature increases) at a large reverse bias, which is associated with the redox reaction of ferrocene groups in the molecular junction, is found. It is further demonstrated that the molecular devices can function on flexible substrates under various mechanical stress configurations with consistent electrical characteristics. This study enhances the understanding of asymmetric molecules and may lead to the development of functional molecular electronic devices on both rigid and flexible substrates.     

A Possible Reaction Pathway to Fabricate a Half‐Metallic Wire on a Silicon Surface

Based on first‐principles electronic structure calculations and molecular dynamics simulations, a possible reaction pathway for fabricating half‐metallic Mo‐borine sandwich molecular wires on a hydrogen‐passivated Si(001) surface is presented. The molecular wire is chemically bonded to the silicon surface and is stable up to room temperature. Interestingly, the essential properties of the molecular wire are not significantly affected by the Si substrate. Furthermore, their electronic and magnetic properties are tunable by an external electric field, which allows the molecular wire to function as a molecular switch or a basic component for information storage devices, leading to applications in future molecular electronic and spintronic devices.     

有机分子纳米线的合成及其导体性质

分子导线是分子电子学研究的重要内容,是分子电子器件的基础。结合分子导线的电子传导性对获取有机线性分子的方法进行了论述。指出共价合成法具有形貌和电子传递的可控性,但合成及纯化的困难限制了其进一步发展。自组装法尽管存在着结构缺陷,而且目标线性分子的直径和维度也难以控制,但其制备方法简单、灵活,所以是有机分子导线的主要研究方向。对一些研究者以自组装法为基础,通过分子间弱的相互作用、定向原子堆积、配位键等研发出的新的有机线性分子建构方法进行了介绍。目前,有机线性材料尽管在微纳电子器件的应用中很难与无机材料竞争,但其作为无机材料的补充,展示了良好的应用前景。     

Atomistic study of three-leg molecular devices

Molecular electronics is one of the promising technologies for future electronic applications that is currently gaining a lot of interest. This is because if single molecule could be used as active electronic components this would provide an ultimate device miniaturization. Previously studied molecules provide almost exclusively two terminal devices. In this paper, three-leg molecular devices are examined employing a first-principles study based on density functional theory coupled to the non-equilibrium Green’s function formalism. We illustrate the feasibility of building a prototype molecular transistor using three-leg molecules directly contacted to gold electrodes. We discuss the different factors that control the transport through this molecular transistor. Moreover, we show that a functional standalone NAND logic gate can be implemented using a single three-leg molecular device.     

Towards Integrated Molecular Electronic Devices: Characterization of Molecular Layer Integrity During Fabrication Processes

Reproducible carbon/molecule/Cu molecular junctions are made with high yield using diazonium reduction of aromatic molecules on carbon with direct evaporation of Cu as a top contact. This report investigates the stability of these devices in response to fabrication steps. Raman spectroscopy through a transparent support shows that direct deposition of Au or Cu causes little change in molecular layer structure, while Ti and Pt deposition cause significant damage to the molecules. AFM, Raman, and XPS examination of Au, Cu, and Ti devices after removal of deposited metal confirm that Cu and Au have minimal effects on molecular structure. However, the molecular layer is rougher after Au deposition, probably due to partial penetration of Au atoms into the molecular layer. Completed carbon/molecule/Cu devices can be heated to 250 °C without significant changes in electronic behaviour while nitroazobenzene molecular layers on carbon were unaffected by photolithography or by 5 min at 400 °C in vacuum. Completed devices could be sealed with parylene‐N, stabilizing them to aqueous etching solution. The stability of carbon/molecule/Cu junctions is due, in part, to the strong carbon–carbon bonding and aggressive nature of diazonium surface modification. The results significantly expand the range of processing variables compatible with molecular electronic junctions.