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Title:Unlocking single molecule detection sensitivities in surface-enhanced Raman spectroscopy
Author(s):Grewal, Sartaj S.
Advisor(s):Lyding, Joseph W.
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Surface-enhanced Raman spectroscopy (SERS)
Abstract:Single molecule detection sensitivities in surface-enhanced Raman spectroscopy require uniform fabrication of sub-5nm gaps between plasmonic nanoparticles over large areas. For this purpose, researchers have employed ultra-precise fabrication techniques like electron-beam lithography that offer very high resolution, but suffer from low throughput. This thesis proposes a novel solution that combines parallel fabrication techniques of nanosphere lithography and Langmuir- Blodgett assembly with the ability to tune interparticle gaps on stretchable polydimethylsiloxane substrates to fabricate sub-5nm gap bowtie arrays. Toward that end, centimeter-scale nanosphere assembly with large grain sizes of 150μm is demonstrated for hydrophilic silicon substrates. The resulting hexagonally symmetric gold bowtie arrays present three different bowtie motifs that are characterized by 0o, <60o and 60o differences between the grain orientation direction and the evaporation direction. Subsequently, a new polydimethylsiloxane (PDMS) fabrication recipe is developed for making large area stretchable substrates and a hydrophobic nanosphere assembly process results in assembled colloidal mask layers on PDMS substrates equivalent in quality to the colloidal mask layers on silicon substrates. Finally, linear tuning of bowtie gaps with modulation of strain in underlying PDMS substrates is proved.
Issue Date:2017-02-10
Rights Information:Copyright 2017 Sartaj S. Grewal
Date Available in IDEALS:2017-08-10
Date Deposited:2017-05

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