二环硅烷的合成及其单分子导电性研究

发布时间：2018-07-03 12:06

本文选题：二环硅烷 + 扫描隧道显微镜断裂分子结测试　；参考：《上海师范大学》2016年硕士论文

【摘要】：单晶硅在半导体材料中占据着重要的地位,其化学结构是由Si-Siσ单键相互连接而形成的正八面体结构。金刚烷与单晶硅具有相同的空间结构,但两种材料的物理、化学、电学性能却有本质上的差异。分子形态是宏观单晶硅半导体材料的主要组成部分。由摩尔定律可知,半导体器件尺寸会越来越小,硅电子器件也有同样的趋势。当硅电子器件尺寸从宏观状态变成小分子尺度——单个有机硅分子,宏观下的电学规律将不再适用。因此研究纳米尺度下有机硅分子的电子行为具有非常重要的科学意义。目前已知,导电通路和分子张力是影响单分子电导的重要因素,我们期望通过对这两个因素的可控调节,来研究它们对有机硅分子电导性能的影响。本论文的主要研究内容是二环硅烷结构的电子传递特性。目前已报道的二环硅烷结构有很多,例如:二环[2.2.1],[2.2.2],[1.1.1]硅烷等。相比于已报道的结构,本论文的一个突出特点在于,经过特定的修饰,可以使环硅烷连接在单分子器件中,进而能测试其电子传输特性。扫描隧道显微镜断裂分子结(STM-BJ)测试是一种被广泛应用于研究电子迁移机理的基础实验方法,该方法将有机分子连接在针尖与金属基底之间,并测试单一分子的电子传递性能。例如:STM-BJ测试不仅可用于研究电子传递机理(隧穿、共振跃迁或连续跃迁),还可以了解载流子的本质(电子或空穴)。STM-BJ测试不仅为分子电子学的发展提供强大的实验手段,同时还可以用于研究有机硅单分子器件的电子迁移情况。本文合成了一系列功能化的二环硅烷,并将它们连接在STM的金属针尖与基底之间,测试了该类二环硅烷的单分子的电学行为。经过对实验结果的分析,得到以下几点结论:(1)二环硅烷:二环[2.2.1]、[2.2.2]硅烷都有一个导电状态,且二环[2.2.1]硅烷的电导比二环[2.2.2]硅烷高。(2)外接硅链二环硅烷:二环[2.2.1]、[2.2.2]硅烷的电导都随着链长增加而降低,这符合隧穿机理。所得到的二环[2.2.2]硅烷的隧穿系数β=0.55±0.14,课题组测出直链硅烷β=0.7。外接不同长度硅链的二环[2.2.2]硅烷隧穿系数与直链结构相似。其原因可能是纳米尺度下电子的传输与宏观状态下有很大的不同,二环[2.2.2]硅烷虽然增加了导电通路,但并未出现宏观电路中类似并联电路的结果。
[Abstract]:Monocrystalline silicon plays an important role in semiconductor materials. Its chemical structure is a normal octahedral structure formed by the connection of Si-Si 蟽 single bond. Adamantane has the same spatial structure as monocrystalline silicon, but the physical, chemical and electrical properties of the two materials are essentially different. Molecular morphology is the main component of macroscopical monocrystalline silicon semiconductor materials. According to Moore's law, semiconductor devices will be smaller and smaller, silicon electronic devices have the same trend. When the size of silicon electronic device changes from macroscopic state to small molecular scale-a single organosilicon molecule, the macroscopic electrical law will no longer be applicable. Therefore, it is of great scientific significance to study the electronic behavior of organosilicon molecules at nanometer scale. It is now known that conduction pathways and molecular tension are important factors affecting the conductivity of monolayers. We hope to study their effects on the conductivity of organosilicon molecules through the controllable regulation of these two factors. The main content of this thesis is the electron transfer characteristics of dicyclic silane structure. Many structures of dicyclic silane have been reported, for example: dicyclo [2.2.1], [2.2.2], [1.1.1] silane and so on. Compared with the reported structure, one of the outstanding features of this paper is that the cyclosilane can be connected to the monolayer device by special modification, and the electron transport characteristics of the device can be tested. Scanning tunneling microscope fracture molecular junction (STM-BJ) measurement is a basic experimental method which is widely used to study the electron transport mechanism. It connects organic molecules between the tip of the needle and the metal substrate and tests the electron transfer properties of a single molecule. For example, the: STM-BJ test can be used not only to study the mechanism of electron transfer (tunneling, resonant transition or continuous transition), but also to understand the nature of carriers (electrons or holes) .STM-BJ testing not only provides a powerful experimental means for the development of molecular electronics. It can also be used to study the electron migration of organosilicon monolayers. A series of functional dicyclic silanes have been synthesized and connected between the metal tip of STM and the substrate. The electrical behavior of the monolayers of this kind of dicyclic silanes has been measured. Through the analysis of the experimental results, the following conclusions are obtained: (1) the bicyclic silane: bicyclic [2.2.1], [2.2.2] silane has a conductive state, The conductance of bicyclic [2.2.1] silane is higher than that of bicyclic [2.2.2] silane. (2) the conductance of binocyclic [2.2.1] silane and [2.2.2] silane decrease with the increase of chain length, which is consistent with the tunneling mechanism. The tunneling coefficient of dicyclic [2.2.2] silane is 0.55 卤0.14. The two-ring [2.2.2] silane tunneling coefficient with different lengths of silicon chains is similar to that of straight chains. The reason may be that the electron transport at nanometer scale is quite different from that in macroscopic state. Although the bicyclic [2.2.2] silane increases the conduction path, there is no parallel circuit in macroscopic circuit.
【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O627.41

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