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Determination of the Excitation and Coupling Rates Between Light Emitters and Surface Plasmon Polaritons
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Electrical tuning of a quantum plasmonic resonance
Xiaoge Liu1, Ju-Hyung Kang1, Hongtao Yuan1,2,3
1Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA.
Nature Nanotechnology
|June 13, 2017
Summary
Quantum size effects in indium tin oxide (ITO) films were actively tuned using electrical gating. This research demonstrates a controllable blue-shift in surface plasmon resonances, overcoming challenges in studying quantum phenomena in metallic films.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanophotonics
Background:
- Surface plasmons (SPs) confine light in subwavelength volumes, enabling strong light-matter interactions.
- Classical models explain SP resonances in noble metals, but quantum size effects emerge at nanometer scales.
- Studying quantum size effects in metallic films is challenging due to carrier confinement in only one direction.
Purpose of the Study:
- To demonstrate active tuning of quantum size effects in surface plasmon resonances.
- To investigate the impact of electrical gating on the plasmonic response of thin metallic films.
- To explore the use of indium tin oxide (ITO) as a tunable plasmonic material.
Main Methods:
- Utilized a 20-nm-thick indium tin oxide (ITO) film, a low-carrier-density Drude metal.
- Employed an ionic liquid (IL) for electrical gating to partially deplete the ITO layer.
- Measured shifts in surface plasmon resonances under varying electrical bias.
Main Results:
- Observed a controllable and reversible blue-shift in the surface plasmon resonance above a critical gate voltage.
- A quantum-mechanical model accurately reproduced the experimental results, including the observed blue-shift.
- Classical models failed to predict the experimental observations, highlighting the importance of quantum effects.
Conclusions:
- Electrical gating provides an effective method for actively tuning quantum size effects in plasmonic films.
- Indium tin oxide (ITO) is a viable material for demonstrating tunable quantum plasmonics.
- Quantum-mechanical descriptions are necessary to accurately model plasmonic behavior in nanostructured materials at the quantum limit.
