Electrical & Computer Engineering, Department of


Date of this Version



A dissertation presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Doctor of Philosophy. Major: Engineering; Under the supervision of Professor Yongfeng Lu Lincoln, Nebraska: December, 2008. Copyright © 2008 Kaijun Yi.


To satisfy the development of nanoscience and nanotechnology, techniques to characterize and fabricate nanostructures and nanodevices are in great demand. Laser, as a unique monochromatic and coherent light source, meets the needs because it exhibits the potential to reveal some vital information of the materials. However, the applications of laser technology to nanoscience and nanotechnology are facing a severe challenge: the spatial resolution cannot be further enhanced to achieve nanometer scales due to the optical diffraction limit associated with conventional optics. In response to this challenge, near-field optics has been emerging as a new scientific area to deal with optical phenomena at that scales. The objective of this dissertation is to explore the possibility and extend the capability of laser technology into the fabrication and characterization of nanostructures and nanodevices using near-field optics. With the aim of establishing a frame to this objective, our goals of this study are to develop novel optical characterization techniques and platforms with nanoscale resolutions, and to fabricate nanostructures using laser technology.

First, theoretical studies on the optical near fields induced by microparticles, metallic tips and metallic nanostructures were accomplished by using the Finite-Difference-Time-Domain method. Secondly, based on a micro-Raman spectrometer, a nano-Raman spectrometer was developed by using a scanning tunneling microscope in combination with side-illumination optics. The spatial resolution of 20 nm of this instrument was demonstrated by mapping single-walled carbon nanotubes. Thirdly, assisted by using metallic nanostructures, the Raman enhancement was further improved by one order. Fourthly, using self-assembled silica microparticles, the Raman enhancement was observed. This technique has a spatial resolution of 100 nm. Fifthly, using the developed techniques, the properties of the single-walled carbon nanotubes were systematically studied through spectral characterization and Raman imaging. Finally, highly conductive Si nanostructures with a feature size of 30 nm were fabricated using a laser-assisted scanning tunneling microscope. The developed techniques have the capabilities of fabricating nanostructures and characterizing their topographic, electronic, mechanic, thermal and optical properties systematically.