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Details of hydrodynamic focusing in a 2D microfluidic channel-junction are investigated experimentally and theoretically, especially the effect on the focusing width of volumetric flow ratio r between main and side channels, as well as angle h between channels. A non-linear relationship is observed where the focus width decreases rapidly with increasing r and levels off at higher values. For the dependence on h, results from both experiments and modeling show that an increased focusing effect is obtained as h approaches 90°. Long-range focusing is explored along a 1 cm long channel and it is observed that in the middle section of the channel, a smaller h induces less divergence. This effect is of importance for microfluidic systems utilizing hydrodynamic focusing in long, straight channels.

Raman microscopy has been used for a direct comparison between furnaceand laser-annealing techniques on polysilicon, and also between phosphorus-implanted and non-implanted polysilicon samples. Variations occurring as a result of different annealing temperatures and energies have been analysed and compared to optical reflectivity data. Measurements have also been carried out to determine the uniformity and extent of anneal produced by laser annealing, and hence the success of this alternative annealing technique. It has been shown that furnace-annealed polysilicon has structural properties most closely resembling those of single-crystal silicon, with large stresses being induced in the laser annealed material.

The temperature dependent refractive index of amorphous silicon has been measured at a wavelength of 820nm from room temperature up to nearly the melting point close to 1200°C. The method employed is to use a single pulse from a XeCl excimer laser to heat the silicon without crystallizing it and to measure the transient reflectivity. This is then modeled by converting a calculated temperature profile into an effective multilayer structure and calculating the reflectivity using a transfer matrix formulation. The refractive index is optimized using simulated annealing. The real part of the refractive index is found to vary linearly with a temperature coefficient of 3.85×10−4 while the extinction coefficient is found to vary as exp(3.82×10−3T), with T=0 at room temperature.