NANOFABRICATION AND TESTING OF PHOTONICS AND ELECTRONICS DEVICES

Abstract

Nanotechnology, with its ability to manipulate matter at the smallest scales has become the cornerstone of modern optoelectronics. One nanometer is equivalent to one billionth or 10-9 of a meter. To put the scale into perspective, the size of a nanometer compared to a meter is similar to the size of a marble compared to the earth. Nanofabrication, arises from nanotechnology, focuses on the methods to build the nanometer scale components, and features with precise accuracy. Through advancements in nanotechnology, photonic devices are tailored to achieve the remarkable control over light at nanoscale dimensions which includes nanostructures for antireflection coatings to enhance the transmission and planar meta lenses to precisely focus the light at certain focal length. Antireflection coatings are used to suppress reflection and increase the optical transmissions, however, these coatings whether it is single layer, or multi-layer cannot withstand the harsh environmental conditions and generally suffers from degradation which deteriorate its optical performances. Inspired from moth eye, subwavelength structures designed periodically were fabricated on the III-V materials, specifically gallium arsenide, to increase its transmittance in the mid-infrared (mid-IR) range wavelengths. Nanopillars structures were fabricated using the top-down approach to pattern the structures directly on the substrate. By varying the pitch of nanostructures, further improvement in the transmission was measured and the results were validated using the rigorous coupled wave analysis (RCWA) model. Similar nanostructures but much smaller in size were written using the E-beam lithography technique on polysilicon coated quartz sample to focus and reflect the light back at the incident direction. The meta lens was first designed by choosing the phase profiles and simulating the different size nano atoms to generate the transmission and phase values chart. Mapping the phase profile against the correct position of meta-atoms helps to produce the desired delays across the lens.Electronic devices, on the other hand, manipulate the movement of electrons instead of light to process the information. Traditional electronic devices such as MOSFETs and BJTs suffers from charge carrier and low electron mobility which makes them less preferred choice for high frequency applications. High electron mobility transistors or simply HEMTs, which possess reduced scattering and high electron mobility, are therefore used for advanced microwave and millimeter applications. Herein, I have also fabricated InP based HEMTs for the terahertz image detection utilizing the techniques such as MBE, PVD, wet etching and lift off.