Date of Graduation

5-2016

Document Type

Thesis

Degree Name

Bachelor of Science in Mechanical Engineering

Degree Level

Undergraduate

Department

Mechanical Engineering

Advisor/Mentor

Millett, Paul

Committee Member

Couvillion, Rick J.

Abstract

Plasmonic nanostructures have been shown to act as optical antennas that enhance optical devices due to their ability to focus light below the diffraction limit of light and enhance the intensity of the incident light. This study focuses on computational electromagnetic (CEM) analysis of two devices: 1) GaAs photodetectors with Au interdigital electrodes and 2) Au thin-film microstructures. Experiments showed that the photoresponse of the interdigital photodetectors depend greatly on the electrode gap and the polarization of the incident light. Smaller electrode gap and transverse polarization give rise to a larger photoresponse. It was also shown that the response from the introduction of the Au thin-film microstructure in the electrode structure was greater. The experimental device enhancement found for the introduction of the thin-film microstructures is most likely attributed to hot electron excitation. This computational study will simulate the optical properties of these two devices in order to determine what plasmonic properties and optical enhancement these devices may have. The modeling software used to validate the experimental results solved Maxwell’s equations with a finite element method (FEM) mathematical algorithm provided by COMSOL Multiphysics. For the interdigital photodetectors device, it was determined that the device response as a function of electrode gap and incident light polarization angle were similar to the experimental results. The enhancement provided by the introduction of the Au thin-film microstructures cannot be completely explained by plasmonic activity occurring with the microstructures, but there is plasmonic activity occurring with the devices.

Comments

I would like to thank Dr. Joseph Herzog for taking a chance on a sophomore with no research experience and inviting me to join his research group. I would also like to thank Ahmad Nusir for fabricating and performing all experimental tests for the devices in this work and the concurrent support he received from Dr. Omar Manasreh. I would like to thank Dr. Woodrow Shew, Dr. Paul Millet, and Dr. Joseph Herzog for serving on my honors thesis committee.

I would also like to thank Ahmad Nusir for fabricating the electrode devices in this work as well as experimentally testing all of the devices. I would also like to thank Stephen Bauman for his help with fabricating other nanodevices that contributed to other works. I would like to thank Jonathan Mishler, Cameron Saylor, Eric Novak, Paul Nguyen, and Grant Abbey for aiding the simulation process and for meaningful conversations about COMSOL.

I would also like to thank my wife, for putting up with the many hours that I spent conducting research, compiling data and figures, and putting this paper and presentation together. P.s. I did not cure cancer.

Note: This work has been submitted and published in [8] and [10] and another is in progress [23]. Other computational work completed by A. Hill was submitted and published in [26].

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