Mechanical and electronic measurements based on scanning probe microscopy for single molecules on surfaces using electron resonant interaction

本研究的目的是利用我们发明的偏置电压非接触原子力光谱(BIAS NC-AFS)来分析固体表面上制备的具有光电子器件潜力的功能性单分子的结构、结合态和电子态。偏置NC-AFS是一种基于扫描探针显微镜(SPM)的纳米机械光谱学。我们的目的也是建立这种利用施加和扫描针尖和样品之间的偏置电压引起的费米能级能量移动来评估纳米结构的方法。为此，我们研制了超高真空偏置NC-AFM/S，并对该方法进行了改进，旨在开发基于商用石英音叉的力传感器。此外，我们与东北大学的一个团队合作，实验设计并制作了弯曲型和拉伸型石英力传感器，并在清洁的硅尖上生长了Ge团簇，作为功能化的AFM尖端。由于晶格失配的应变生长，团簇具有特定的小面结构。然后，被小平面包围的角变得更锐利，这适用于定义良好的扫描尖端。我们试图用商用原子力显微镜获取原子力显微镜图像。因此，与使用未覆盖的Si针尖相比，使用Ge团簇针尖可以提高空间分辨率。在磨损后，我们在超高真空中加热磨损的Ge团簇尖端，通过重塑Ge团簇来重新磨尖尖端。由于Ge团簇在Si表面的小面结构非常稳定，我们通过多次加热使其重新变硬，这意味着我们获得了一种在尖端重现具有相同电子态的尖端的方法。我们在超高真空中将它与4，4“-二氨基-对三苯基(DAT)共轭分子沉积在Si(111)7x7上，并用扫描电子显微镜研究了它们的吸附状态。

The purpose of this study is to analyze the structures, binding states and electronic states of functional single molecules with potential for opto-electronic devices fabricated on solid surfaces by bias-voltage non-contact atomic force spectroscopy (bias nc-AFS), invented by ourselves. The bias nc-AFS is a nanomechanical spectroscopy based on scanning probe microscopy (SPM). Our aim is also to establish this method to evaluate nano-structures using the energy shift of Fermi level induced by applying and sweeping the bias voltage between a tip and a sample.Here we developed ultra-high vacuum (UHV) bias nc-AFM/S together with improvement of the method, and aimed at developing of force sensors based on a commercial quartz tuning fork. In addition, we experimentally designed and fabricated a bending type and a stretching type of quartz force sensors in cooperation with a group in Tohoku University.Furthermore, we grew Ge clusters on a clean Si tip as a functionalized AFM tip. The clusters have specified facetted structures owing to a strained growth with lattice mismatch. Then the corner surrounded with the facets becomes sharper that is applicable to a well-defined scanning tip. We tried to obtain AFM images with it using a commercial AFM. Consequently, the spatial resolution was improved by using the Ge cluster tip compared with that using an uncovered Si tip. After wearing the tip we heated the worn Ge cluster tip in UHV, resulting in resharpening the tip apex with remolding a Ge cluster. Since the facet structure of a Ge cluster on Si is very stable, we resharpened it many times by heating, implying that we acquire a way to reproduce a tip having the same electronic states on the tip apex.We deposited it -conjugated molecules of 4,4"-diamino-p-terphenyl (DAT) on Si(111)7x7 in UHV, and examined their adsorption states using SPM.