| Due to its excellent physical and chemical properties, the low dimensional nano system has received extensive attention in recent years. Because of its high strength, ex-cellent optical properties, excellent electrical conductivity and heat transfer properties, graphene has been a hot topic in condensed matter physics since its birth in 2004.When the graphene size turn from infinite to finite, the boundary and the nature of the surface is more obvious and easy to characterize. Graphene nanoribbons is such a one-dimensional model of carbon nano materials, its specific edge states have a different nature compared to graphene in the field of electrical, magnetic and chemical etc.Among them, the band width is the most important parameter to control the prop-erties of graphene nano ribbons. The researchers explored the top-down methods such as oxygen ion etching method, ultrasonic method of solution, Ni nanoparticles etch-ing method, cutting method of multi wall carbon nanotubes, and bottom-up solution synthesis mthods such as aromatic molecule synthesis method to synthesize graphene nanoribbons with specific width.In the second chapter, we by using low temperature scanning tunneling microscopy studies two kinds of chemical of the same molecular (pentacene molecule and picene molecules) on the Au (110)-1*2 templates. Due to the Au substrate (110)-1*2 recon-struction’s one-dimensional limit, we used pentacene and picene molecules as the pre-cursor, synthesized one-dimensional and quasi one dimensional graphene nanoribbons. At the same time, in this process, we elaborate the dehydrogenation polymerization process and molecule substrate mutual interaction between the molecules and Au (110)-1*2 template, which affected the reaction directions. Besides, we investigated on the molecular intrinsic properties’s effects on the one-dimensional chain properties.Pb/Si (111) system is a model of the growth of metal on the semiconductor surfaces and the researchers have long been concerned about. This is because the system has strong quantum size effect. When the metal and semiconductor contact, Fermi level of the two materials was leveled, resulting from one party to the other party’s charge transfer. When the electron is excited from the metal to the conduction band of the semiconductor, it needs to overcome the Schortky barrier. Precisely because of this electron transfer to Pb Island, which concern the total energy of the quantum size effect and for Pb island is very important to determine the position of the Fermi surface.Researchers’focus on the Pb/Si system in recent decades is how to get the atomic level of smooth of the Pb film surface. Secondly, when low temperature growth way was proved to be feasible, researchers concentrated on the layer stability at low tem-perature, which is called Pb/Si (111) "magic stability". After the growth of different layers, the formation of thin films was studied by photoelectron spectroscopy, X-ray diffraction and superconductivity. And relatively, the Pb/Si (111) films obtained after the low temperature growth are more rough compared with the films annealed, and the attention is also lower.In the third chapter, we grew the Pb thin nano-films on reconstructed Si(111)-7×7 substrates by molecular beam epitaxy in the ultra high vacuum chamber. The pa-rameters of Pb films sizes, step heights and film thickness distribution under different growth-rates were analyzed, and the surface morphology of thin films under different deposition-rates was studied. Based on the morphology of Pb thin films, we proposed dependence of growth-mode and deposition-rate of Pb thin nano-films growth on the surface of low temperature Si(111)-7×7.In a word, with the increase of the growth temperature, the growth model of the thin film grows from the Volmer-Weber model to the Stranski-Krastanov model. |
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