Optical Science and Engineering ETDs

Publication Date

Fall 12-17-2018

Abstract

Plasmonic modes in metal nanostructures enable light confinement at subwavelength scales. This field confinement is important for exploring the potential of nanotechnology in miniaturization of optics as well as for the advancement of optoelectronic devices, such as photodetectors, photovoltaics, and light-emitting diodes. Plasmon resonances are also ideal for developing ultrasensitive biosensors, and for enhancing surface photochemistry and photocatalysis. The increasing number of plasmon applications requires fundamental understanding of the plasmon coupled system which has not yet been completely understood. Controlling and engineering the plasmon response at the nanoscale will open still more applications in material science, communications, biochemistry and medicine.

In this dissertation, the optical interactions between resonant plasmonic nanoparticles and both polarizable semiconductor substrates and metallic films have been investigated by analyzing the scattering properties of the plasmonic nanoparticles and the photoluminescence (PL) of emitters embedded in the semiconductor substrate. Fundamental studies of the coupling of the localized surface plasmon resonance of colloidal gold nanoparticles with III-V semiconductor quantum dots (QDs), and metallic gold-films have been carried out. By coupling colloidal gold nanorods (AuNRs) to InAs QDs, embedded in InGaAs/GaAs quantum well, plasmon enhanced carrier generation and photon emission are investigated by monitoring the PL intensity enhancement at room temperature. The length scales of the near-field confinement, carrier diffusion, and excitation energy transfer to the metal surface (that leads to quenching of PL at small AuNR-InAs separation distances), have been determined systematically both experimentally and theoretically by varying the GaAs capping layer thickness. After establishing the dependence on separation, the temperature dependence of plasmon enhanced carrier generation and photon emission are studied by analyzing QDs PL.

Atomic layer deposition (ALD) of Al2O3 dielectric spacer layers is developed for precise, atomic scale control of separation and uniform conformal deposition. Using the AuNR-SiO2 system as a reference, the optical interaction in a AuNR-GaAs system separated by a ALD Al2O3 dielectric spacer is explored. Super-resolved optical interaction has been demonstrated for the metallic gold particle-film system separated by Al2O3 spacer layer. Controlling the spacer layer thickness at a sub-nanometer length scale provides the opportunity to experimentally examine the transition from the classical to quantum mechanical regime. The optical coupling in a metallic particle-film system is investigated from capacitive to conductive junction. These fundamental analysis may help to advance the development of plasmonic devices.

Degree Name

Optical Science and Engineering

Level of Degree

Doctoral

Department Name

Optical Science and Engineering

First Committee Member (Chair)

Terefe G. Habteyes

Second Committee Member

Steven R. J. Brueck

Third Committee Member

Kavin Malloy

Fourth Committee Member

Francesca Cavallo

Fifth Committee Member

Igal Brener

Keywords

plasmonics, quantum dot, III-V semiconductor, metal particle-film, charge transfer plasmon, quantum tunneling

Document Type

Dissertation

Language

English

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