Study of atomistic diffusion, nucleation and cluster formation process of atoms and molecules

近年来，由于表面探针显微镜，特别是扫描隧道显微镜（STM）的发展，使观察固体表面上单个原子或单个分子的原子运动成为可能。本研究的第一个目标是了解单原子在沉积8小时后的原子扩散形成团簇的过程。我们观察了Ag原子在Si(111)7x7表面的原子运动和（Ag）n簇在7x7表面电位中的形成过程。发现跳跃速率依赖于最近邻的位置时，扩散是合作的。我们还测量了隧道光谱，发现n=5和6簇具有特定的电子能级。第二个目标是研究底物与吸附质原子或分子之间最弱的相互作用。我们在端氢Si（111）表面观察到并五苯多晶薄膜晶体的双外延结构和可通约性。此外，我们在端氢Si（111）表面观察到阶梯诱导的并五苯薄膜晶体的各向异性生长。在本研究的前期，我们提出了超清洁和原子控制端氢Si(111)-(1x1)表面的工艺，并通过高分辨率电子能量损失谱、原子力显微镜和扫描隧道显微镜揭示了这一工艺。我们还提出了氘端Si（111）表面，并观察了表面声子。第三个目标是研究底物与吸附原子之间的强相互作用。利用STM研究了硅化铂薄层的形成过程和表面结构。现在，我们能够操纵单个原子或分子，然后，我们试着估计簇的大小和电子结构。我们的最终目标是了解簇的形成过程，表面反应，并在原子尺度上形成电子器件。

Recently, it is possible to observe atomistic motion of single atoms or single molecules on solid surfaces due to the development of surface probe microscopy, in particular scanning tunneling microscopy (STM). First goal of this study is to understand a cluster formation process from atomistic diffusion of single atoms, just after deposition up to 8 hours. We observed the atomistic motion of Ag atoms on a Si(111)7x7 surface and the formation process of (Ag)n clusters in a 7x7 surface potentials. It is found that the diffusion is cooperative where the hopping rates depend on the nearest neighbor sites. We also measured the tunneling spectroscopy and found that the n=5 and 6 clusters have a specific electronic energy level: Second goal is to investigate the weakest interaction between substrate and the adsorbate atoms or molecules. We observed two -epitaxial structures of pentacene polycrystalline thin film crystals on a hydrogen-terminated Si(111) surface and commensurabilites. Furthermore, we observed the step-induced anisotropic growth of pentacene thin film crystals on a hydrogen-terminated Si(111) surface. In the early stage of this study, we proposed the process for ultra-clean and atomically controlled hydrogen-terminated Si(111)-(1x1) Surface and it is revealed by high resolution electron energy loss spectroscopy, atomic force microscopy and scanning tunneling microscopy. We also propose the deuterium terminated Si(111) surface and observed the surface phonons. Third goal is to investigate the strong interaction between substrate and the adsorbate atoms. Formation process and surface structure of platinum silicide thin layers was studied using STM.Now, we are able to manipulate the single atom or molecule and, then, we try to estimate the cluster size and the electronic structure. Our final goal is to understand the cluster formation process, surface reaction and to form an electronic devices in the atomic scale.