Nano-structuring using pulsed laser radiation

Surface nanostructuring of various films at high spatial resolutions was performed with great accuracy and reproducibility by using two near-field optical methods. Nanostructures were defined with minimum lateral feature dimensions of ∼10 nm and various complex nanopatterns were produced on metal thin-film samples. Experimental ablation results on Au thin-films and numerical simulation results for the electric field intensity and temperature distribution in the films provided useful insight into the laser thin-film interaction dynamics at the nanoscale. Nanoscale melting and rapid crystallization of a-Si films using a nanosecond laser source was demonstrated using the both apertured and apertureless NSOM schemes. The ability to nucleate and produce these single nanostructures in a controlled fashion could open up a number of potential applications. Further, LCVD based nanodeposition study results were presented using the apertured NSOM scheme which provides us with a useful tool to produce arbitrary shaped three-dimensional nanostructures. Use of thin metal films as effective masking layers was demonstrated wherein ablated nanopatterns generated on metal masking layers were effectively transferred on to the underlying transparent quartz substrate. Using arrays of scanning microprobe tips with integrated actuator and sensor mechanisms could lead to increased throughput of these surface nanostructuring schemes. Furthermore, by incorporating improved probe designs with dedicated waveguide structures or using switching devices like digital micromirror arrays, precise optical delivery schemes could be devised for coupling the beam with the microprobe tips. Possible applications of these nanostructuring processes are envisioned in high-resolution nanolithography, controlled nanodeposition, ultrahigh density data storage, mask repair, nanoelectronics, nanophotonics, and various nanobiotechnology applications.