Date of Award

2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Graduate Group

Materials Science & Engineering

First Advisor

Ritesh Agarwal

Abstract

Nanowires (NWs) and nanobelts (NBs) have been widely studied and fabricated into on-chip photodetectors, biosensors, LEDs/lasers, solar cells and computational components. Their highly tunable physical, electronic and optical properties have generated interest in this field over the past two decades. While there is tremendous potential for nano-structured devices, the wide spread application of NWs/NBs has been hindered by the difficulty in integrating multiple NW or NB structures together into more complex devices. This problem requires a completely novel approach to what has been previously attempted in order to effectively couple on-chip light sources, waveguides and detectors. Multiple factors must be considered including optical power of nanoscale light sources, propagation losses in waveguides and responsivity of nano-scale detectors. Only in combination is it possible to have fully on-chip integrated devices. In this thesis we report the design, optimization and fabrication of coupled self-aligned NB LED emitters and photodetectors. An etched cut is made into a single Cadmium Sulfide NB providing the ability to fabricate each section of a single NB into a separate device. This opens possibilities for on-chip devices such biological sensors. This self-aligned structure can also be coupled to an external light source. Additionally, we present a method for waveguideing and modulating second harmonic generation (SHG) in Cadmium Sulfide NBs as a light source for on-chip measurements. SHG is a coherent and tunable frequency doubled light source so the input laser does not interfere with measurements on-chip. The ability to reliably fabricate more complex devices with nano-structures will continue the trend of portability and point-of-care technology by integrating bulk components such as lasers and photodetectors onto on-chip devices.

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