Electromagnetic wave scattering from surfaces with random and deterministic roughness.

摘要

The radiative properties of engineering surfaces with microscale surface texture or topology are of fundamental and practical importance. The present study examines the optics of thin film, random and periodic surface roughness. A novel transformation technique has been developed to efficiently and accurately simulate time-domain elecrodynamics with periodic boundary condition.; The study on thin film partial coherence is first presented. Unlike the previous approach derived based on degree of coherence, a direct integration approach is developed. The analytical results are in excellent agreement with the measured spectra. Rigorous criteria for incoherent and coherent limits are reduced from the general formulae and the resulting equations corresponding to those of geometric and wave optics, respectively.; It is followed by the study of random roughness effect on radiative properties. The finite-difference time-domain (FDTD) scheme is used to solve Maxwell's equations. Dielectric and metallic 1D rough surfaces and 2D dielectric surfaces are studied. Geometric optics ray tracing method is typically much more efficient than other rigorous methods such as FDTD and integral equations methods. However, it fails when the wavelength is on the same order or larger than the geometrical characteristic size. A new regime map of the ray tracing method is developed with consideration of various incident angles.; The patterned structure of silicon wafers may cause temperature non-uniformity during the RTP process of semiconductors. The influence varies with the factors of geometry, temperature, and wavelength. The study considers two topographies: silicon gates on a silicon substrate; and oxide trenches embedded inside a silicon substrate. The effects of effective medium, interference and resonance cavity are examined.; The simulation of electrodynamics with periodic boundary condition (PBC) is of fundamental difficulties. Traditional methods typically require much more computational load or storage requirement. This study presents a novel instantaneous transformation technique. Different from the Fourier Transform, this technique transforms real time values of a given frequency description of incident waves into the phasor domain instantly, with almost no trade-off in computation effort or storage requirement. It is easy to implement within existing computational electrodynamics models, and this has been done in the 2D FDTD scheme.