Characteristics and Nano-measurements of Fullerene Embedded Si(111) surface using Scanning Probe Microscopy

• Main Authors: Chih-Pong Huang, 黃至鵬
• Other Authors: Mon-Shu Ho
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/11868204203862785750

博士 === 國立中興大學 === 物理學系所 === 99 === Elucidating the effect of size variation in nanoscale has also led to various and unique new physical and chemical properties in materials. Silicon carbide is one of the most important new-generation semiconducting materials, with important applications in various fields. Silicon carbide has promising development potential in the applications related to optoelectronic devices and high-temperature electric devices. Field emission properties of semiconductor carbides have motivated a number of studies because of their application for electron field emission sources. However, a high density of defects, such as micropipes and dislocations, commonly are present on conventional silicon carbide surfaces, potentially affecting the electronic structure, and causing device failure as well. As devices for silicon-based electronics industry are developing to the physical limits, it is urgency to find substituting materials. Fullerene molecules were used instead of carbon souces and silicon was taken as supporting substrate. The interface configuration and growth mode of fullerene molecules on silicon surfaces are very important as an understanding thereof may support the replacement of silicon carbide as a semiconductor material. In this work, the supramolecular structures and orientations of C60 and C84 molecules were studied under a UHV-scanning tunneling microscope. Carbon molecules preferentially appear in faulted halves, rather than in unfaulted halves and corner holes; they are embedded in silicon substrates. The orientations and possible configurations of C60 and C84 are considered in this work. The energy differences for various features of C60 and C84 molecules are estimated and discussed. This study also fabricates a single molecule, nanoclusters, and self-assembled layers of C84 on Si(111) surfaces using special annealing treatments. The electronic density of states related to quantum confinement effect and field emission properties are determined at room temperature using an ultra-high vacuum scanning tunneling microscope and a high-voltage source measurement unit respectively. Additionally, calculations from first-principles method are in good agreement with experimental results. The optoelectronical properties are examined by photoluminescence emission spectroscopy. The stiffness of the Si(111) surfaces with embedded C84 is determined from force-distance curve measurements made using an atomic force microscope in atmosphere environment and ultra-high vacuum respectively. This investigation develops a material with many advantages over conventional silicon carbides and without porous defects, which can therefore be used as a substitute in optoelectronic and electronic devices. We believe that our work has the advantages of conventional silicon carbides but also can avoid the porous defects, and thus is a substitute for optoelectronic and electronic devices. The self-assembled silicon surfaces with embedded C84 have favorable properties for applications in nanoelectronics and optoelectronics. The excellent characteristics of the developed material show nanotechnology consciousness through controlling matter on an atomic and nanoparticle scale. More important properties for fullerene embedded Si substrate will be revealed in the near future.