Fabrication and Evaluation of Nanoscale Quantum Structure Using Functional Organic Molecules

本研究的目的是构建一维分子导线，特别是导电纳米线，并控制其在固体表面的图案，从而用有机分子制作单电子隧道器件。此外，还建立了独立驱动的双尖扫描隧道显微镜(WT-STM)，这是一种新的评估这种纳米结构功能的系统。今年，我们研究了两个组分分子单层的二维有序结构，其中二乙炔化合物和脂肪酸分子平行于HOPG的表面。获得微观混合区域的可能性取决于两个分子的相对长度的比率。通过施加STM尖端的脉冲偏压，利用链式聚合的方法在表面的预定位置成功地制备了聚二乙炔分子导线。我们用WT-STM评价了二乙炔化合物超薄分子片的电导。我们用LB法和紫外光照射法制备了聚二乙炔化合物的六层样品。两个尖端的距离从亚微米到数百微米不等。结果表明，与体相结构相比，其薄膜具有明显的高电导率。认为分子体系的一维结构和微观结构的电子特征与三维宏观结构，即体相分子体系的电子特征有很大的不同。这一结果对构建具有多种高贵功能的纳米级分子器件具有很好的应用前景。

The aim of this research is to construct one-dimensional molecular wires, especially, conducting nanowires, and to control their patterns on the solid surface, consequently, fabricating single-electron tunneling device with organic molecules. In addition, independently-driven double-tip scanning tunneling microscope (WT-STM), which is a novel system to evaluate functionalities of such nanoscale structures, is newly constructed.This year, we investigated the two-dimensionally ordered structures of two component molecular monolayers, in which the molecules of diacetylene compounds and fatty acid lay parallel to the surface on the underlying HOPG. The possibility of obtaining the microscopically mixed regions varied depending on the ratio of the relative lengths of the two molecules. Poly-diacetylene molecular wires can be successfully fabricated at intended positions on the surface using chain polymerization by applying pulsed bias voltage from the STM tip.We have evaluated the conductivity of ultrathin molecular sheet of diacetylene compounds using WT-STM. We made the sample of six layers with poly-diacetylene compounds by LB method and irradiation of UV light. The distances of the two tips were varied from sub-micron to hundreds microns. Obtained results showed a significantly high conductivity of its film compared with that of the bulk structure. It is considered that electronic feature of one-dimensional and microscopic structures of molecular systems are quite different from that of three dimensional and macroscopic, that is, bulk molecular system. And this result is quite promising for the constructions of nanoscale molecular-based devices with various noble functions.