Characterization of metal and semiconductor nanomilling at near threshold intensities using femtosecond laser pulses

Two novel techniques were developed: nanomilling and direct writing of metal surfaces with self-assembled monolayers. This thesis first details the nanomilling of metal surfaces with 800 nm wavelength, femtosecond laser pulses and initial modeling of the microscopic processes in silicon. A careful study of the single shot ablation threshold for copper was carried out yielding an incident single-shot ablation threshold and a reduction in this ablation threshold for multiple shots consistent with an incubation phenomenon. A two-temperature model was used to model the single-shot ablation threshold by describing the coupling of the laser energy to the electron subsystem and the relaxation of this energy to the lattice subsystem through a temperature-dependent energy-coupling equation with a pre-factor commonly referred to as the g-parameter. The g-parameter was similar for all noble metals when the electron thermal conductivity was modeled using the plasma electron conductivity model. The plasma electron thermal conductivity resulted in the independence of the single-shot ablation threshold on pulse width below the electron-lattice thermal coupling time and the adequate prediction of the single-shot ablation threshold for copper.; Nanomilling to depths of less than 10 nanometers required determining the single-shot ablation threshold, incubation coefficient and surface reflectivity. These laser parameters established that surface nanomilling occurred close to the multiple-pulse ablation threshold. Photomultiplier tube measurements of atomic emission during the nanomilling process showed photons emitted once every several shots. The results were consistent with a model that ablation occurred in bursts after a number of intervening incubation energy storage shots.; A methodology was developed to manipulate the surface properties of a self-assembled monolayer (SAM) of alkanethiol on a gold film by using nanomilling. CW laser patterned SAM surfaces created minimum line widths of 4 mum. SAM patterning with femtosecond pulses achieved minimum line widths of (375 +/- 25) nm.; A molecular dynamics simulation of silicon for femtosecond laser pulse ablation was extended to include an electron subsystem to model the avalanche ionization mechanism. The inclusion of avalanche ionization and a parametric study showed the potential of the model to predict the single-shot ablation threshold of silicon over a larger femtosecond pulse range.