SUBJECT: Ph.D. Dissertation Defense
BY: Yu-Bin Chen
TIME: Friday, March 30, 2007, 2:00 p.m.
PLACE: Love Building, 311
TITLE: Rigorous Modeling of the Radiative Properties of Micro/Nanostructures and Comparisons with Measurements of Fabricated Gratings and Slit Arrays
COMMITTEE: Dr. Zhuomin Zhang, Chair (ME)
Dr. F. Levent Degertekin (ME)
Dr. Peter J. Hesketh (ME)
Dr. Gee-Kung Chang (ECE)
Dr. Pei-feng Hsu (MAE, Florida Institute of Technology)


The key to modify or enhance radiative properties is to employ one-, two-, or three-dimensional (1, 2, or 3D) periodic micro/nanostructures, but very few comprehensive studies are available. The present work numerically and experimentally investigates the radiative properties of micro/nanostructures and explores their potential applications such as absorptance of patterned wafer in rapid thermal processing, wavelength-selective radiator design, and nanolithography. The theoretical foundation was built upon the rigorous coupled-wave analysis (RCWA) for numerical calculation of the far-field radiative properties and the electromagnetic field distribution in the near-field regime. Measurements of diffraction efficiencies were conducted on fabricated 1D and 2D periodic silicon microstructures with a high resolution laser scatterometer/diffractometer. A parametric study of radiation absorption from nanoscale patterned wafers was performed to evaluate the applicability of simplified models such as the effective medium approximation for semiconductor manufacturing application. Next, a new concept of complex gratings was proposed for actively tailoring the radiative properties for the design of a wavelength-selective thermophotovoltaic radiator. Furthermore, nanoscale metallic slit arrays were shown to exhibit polarization-dependant transmission characteristics and localized electromagnetic energy density for potential application of nanothermal manufacturing. Three submicrometer slit arrays were fabricated and their spectral transmittance was measured with a Fourier-transform infrared spectrometer. The results largely agree with RCWA predictions. This dissertation clearly demonstrates that precise control and tuning of the radiative properties using micro/nanofabrication are not only feasible but also may have numerous technological impacts.