Narrow Results

The localized surface plasmon (LSP) resonances properties of periodic arrays of nanoholes in thin gold films are investigated by using the method of discrete dipole approximation (DDA). The surface plasmon polaritons (SPPs) play important roles in amplification or suppression of the LSP resonances in the film. The LSP-SPP coupling is affirmed based on the extinction spectra calculated by the DDA. The intensity of the LSP resonances can be controlled through changing the edge-to-edge separation distances between nanoholes, the number and the diameter of the nanoholes. The calculations also indicate that the LSP resonance peak decreases with increasing the thickness of the gold film.

The capability of using Focused Ion Beam (FIB) for milling microchannels is experimentally and theoretically investigated. Microchannel structures are fabricated by a NanoFab 150 FIB machine, using an Arsenic (As²⁺) ion source. A beam current of 5 pA at 90 keV accelerating energy is used. Several microchannel patternings are milled at various dwell times at pixel spacing of 14.5 nm on top of a 60 nm gold-coated silicon wafer. An analytical/numerical model is developed to predict the FIB milling behavior. By comparing with the experimental measurements, the model predictions have been demonstrated to be reliable for guiding and controlling the milling processes.