Fabrication and applications of pillar bowtie nanoantenna arrays

Abstract

This thesis reports the fabrication technique and applications of a pillar bowtie nanoantenna (p-BNA). We use different tools to fabricate our nanostructure, namely, electron lithographic tools, evaporator and plasma chambers. The theory of operation of the machines, especially electron beam lithography for higher resolution, electron beam evaporation for thin film deposition, reactive ion etching (RIE) for high aspect ratio pillar nanostructure and scanning electron microscopy (SEM) for imaging, has been presented. We carefully explain the reasons for choosing each parameter of each tool. For electron beam lithography, we look into the accelerating voltage and dosage parameters to get a high resolution nanostructure. Then we look into electron beam evaporation to come up with the thicknesses for metal deposition. Finally, we come up with the gas flow, pressure, power and etch time parameters for reactive ion etching (RIE) to complete the fabrication of the p-BNA structure. We demonstrate different experiments to show its usefulness in various areas of nanotechnology. We explain the theory to reduce the gap between pillar bowtie nanoantennas using SEM and experimentally show gap size controllability using a combination of accelerating voltage, current and magnification of SEM. Recording near field optical intensity in our nanostructure has been explained via simulation, fabrication and experimental results as well. Moreover, its use in the near infrared wavelength regime as a plasmonic sensor has been theoretically and experimentally demonstrated by increasing the size of the bowtie nanoantennas. Finally, we propose some exciting future work for our p-BNA structure to show its versatile applications in the field of nanotechnology