Fabrication and Optoelectronic Characterization of Nanoscale Resonance Structures

Resonance structures have long been employed by RF and microwave devices ranging from antennas, to wave guides. These resonance structures have exhibited an enormous amount of control over the wavelength selectivity, polarization, and directivity of the electromagnetic radiation which couples to the structure. Traditional geometrical optics has alternatively used discrete optical components such as lenses, gratings, and polarizers to accomplish equivalent control over optical radiation. This dissertation contributes to the larger body of literature that applies lessons learned in RF and microwave resonance structures, to nanoscale resonance structures. Optoelectronic nanoscale resonance structures were fabricated and characterized using both experimental and numerical methods. Two nanoscale resonance structures were investigated: an antenna inspired Yagi-Uda array, and a metasurface inspired interdigitated structure. Experimental devices containing the nanoscale resonance structures were fabricated on semiconducting substrates forming metal-semiconductor-metal photodiodes. The spectral response of the nanoscale resonance photodiode was determined by measuring the photocurrent or photovoltage resulting from incident monochromatic light which was swept through wavelengths from 400 nm to 2000 nm. The previously mentioned Yagi-Uda based device exhibited two maxima in photoresponse at 1110 nm and 1690 nm. Effective wavelength scaling was applied to the Yagi-Uda nanoantenas, and consistency was demonstrated between the theoretical effective wavelength and experimental photoresponse maxima. The spectral response of the interdigitated structure demonstrated good qualitative agreement with the finite element modeled absorbance in an equivalent structure. Analysis of the modeled absorbance suggests that hot electron injection contributes to the photoresponse, and the spectral response of the detector device may be tuned by varying the geometrical parameters of the device. An optimized device was proposed that could improve photodetection efficiency using nanoscale resonance devices. Antenna inspired nanoscale resonance structures may be used to probe fundamental physical phenomena such as hot carrier generation, hot carrier transport, and surface plasmon resonances. Combined optical and electrical-optoelectronic devices exploiting these phenomena may be realized for a variety of applications, eliminating some or all of the discrete optical components required for optoelectronic systems and hence significantly reducing the SWaP cost of optoelectronic systems.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Physics

Department dc:contributor.department

Physics

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2020

Author dc:creator

• Rieger, William Theodore Jr.

Chair dc:contributor.committeechair

• Heremans, Jean Joseph

Committee members dc:contributor.committeemember

• Jia, Xiaoting
• Soghomonian, Victoria Garabed
• Pitt, Mark L.

• nanoantenna
• hot electron

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

vt_gsexam:24877

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/106446