【作者】 何军；

【导师】 陈克求；

【作者基本信息】 湖南大学 ， 物理学， 2009， 硕士

【摘要】 近年来,电子器件的不断小型化激起了人们对分子器件的研究兴趣。目前已经设计出了各种单分子电子器件如分子导线、分子开关、分子二极管、分子场效应管、分子传感器等等,一些新颖的物理现象包括分子开关、分子整流、负微分电阻效应、分子记忆效应等已经被报道了,分子器件将在开关、整流、光电子、记忆器件、逻辑电路等领域有着重要的应用前景。本文基于非平衡格林函数理论与密度泛函理论相结合的第一性原理方法系统地研究了C60分子器件的电子输运性质。研究了由一个C60分子和(5,5)碳纳米管电极组成分子器件的电子输运行为,重点考虑了吸附气体小分子对分子器件电子输运性质的影响。结果表明,吸附H2O分子和CO分子对分子器件的电流-电压特性影响很大,而吸附NO2分子则几乎没有影响。当吸附H2O分子时,我们在特定的偏压区域还发现了明显的负微分电阻现象,本工作也详细分析了负微分电阻效应的形成机理。研究了基于双C60分子与(5,5)碳纳米管电极组成双分子器件的电子输运性质,研究结果表明,通过改变两个C60分子之间的相对距离可以调制分子器件的电学性质。在这样的器件中,我们能实现分子器件的两种开关,即机械调控开关和电控开关,同时我们也观察到了多重负微分电阻效应。这些结果将在分子开关器件方向具有重要的应用前景。更多还原

【Abstract】 In recent years, there have been increasing interest and development efforts in minia-turizing electronic devices. A number of single molecular electronic devices such as molecular wires, molecular switches, molecular diode, molecular field effect transistor (FET), molecular sensor etc. have been designed. Simultaneously, some novel behaviors including switching, coulomb blockade, Kondo resonance, rectification, negative differ-ential resistance (NDR), and memory elements have been reported. Molecular devices will play an important role in switches, rectifiers, photovoltaic, memories, logic circuit in the future. In this thesis, we have systematically investigated the electron transport prop-erties of C60 molecular devices based on first-principles combined with nonequilibrium Green’s function (NEGF) and density-function theory (DFT).The transport behaviors of C60 molecular device constructed by a C60 molecule sandwiched between two (5,5) carbon nanotubes (CNTs) electrodes have been studied, and we have considered the effects of gas adsorption on the electronic transport properties. The results show that the current-bias curves are affected obviously by adsorbed H2O and CO molecule, but hardly effected by NO2 molecule. We also find an obvious NDR behavior at the certain bias while C60 molecular device adsorbed by H2O molecule. A mechanism is proposed for NDR behavior.We investigate the electronic transport properties of a molecular switch device based on double C60 molecules sandwiched between two (5,5) CNTs electrodes. The results show that the electronic transport properties can be tuned by change the relative distance between the two C60 molecules. In this molecular device, we can actualize two sorts of molecular device tuned by mechanism and voltage. These results are promising for application in molecular switch devices.更多还原