Surface Plasmon Behaviors of Metal Nanostructures and Their Coupling with InGaN/GaN Quantum Wells
Date Issued
2012
Date
2012
Author(s)
Chung, Yu-Lung
Abstract
Regularly patterned Ag nanoparticles (NPs) on the surfaces of an InGaN/GaN quantum well (QW) and two QW light-emitting diode (LED) samples are fabricated for inducing localized surface plasmon (LSP) coupling with the QWs based on the nano-imprint lithography technique. From the temperature-dependent photoluminescence (PL) measurements, we observe the shifting of the QW emission wavelength toward the LSP resonance wavelength, the enhancement of PL emission intensity, and the increase of QW internal quantum efficiency. By coating an SiO2 layer on the Ag NPs for protecting the NPs, the LSP resonance wavelength is red-shifted by ~20 nm. To match the QW emission wavelength and the LSP resonance wavelength, we need to make the Ag NPs smaller for maximizing the LSP coupling strength.
Besides, the fabrication and characterization of connected Ag nanodisks in GaN for understanding their surface plasmon resonance behaviors are demonstrated. Regularly patterned Ag nanodisks based on the nano-imprint lithography technique and randomly patterned Ag nanodisks based on the nanosphere lithography technique are fabricated for comparison, particularly for understanding the factor of the periodical pattern. In the randomly patterned samples, only two broad dips, which indicate the SP resonance wavelengths, are observed in the reflection spectra. Howevr, in the regularly patterned samples, other dips are observed, indicating the important effects of the periodical pattern. When the thickness of the Ag nanodisks is increased, the SP resonance features are red shifted.
Subjects
Surface Plasmon
Metal Nanostructures
Quantum Wells
Type
thesis
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