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Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters
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Electrically Driven Hot-Carrier Generation and Above-Threshold Light Emission in Plasmonic Tunnel Junctions
Longji Cui1,2,3, Yunxuan Zhu1, Mahdiyeh Abbasi4
1Department of Physics and Astronomy and Smalley-Curl Institute, Rice University, Houston, Texas 77005, United States.
Nano Letters
|June 23, 2020
Summary
We observed a giant photon yield in plasmonic tunnel junctions, where emitted light energy exceeds incident electron energy. This effect is driven by hot carriers generated from plasmon decay, opening new optoelectronic possibilities.
Area of Science:
- Nano-optics
- Solid-state physics
- Quantum optics
Background:
- Above-threshold light emission in plasmonic tunnel junctions is of significant interest.
- The underlying physics of this phenomenon remains poorly understood.
- Existing models do not fully explain the observed photon yields.
Purpose of the Study:
- To investigate the physics of above-threshold light emission in electromigrated plasmonic tunnel junctions.
- To quantify the photon yield and its material dependence.
- To elucidate the mechanisms driving this non-traditional light emission.
Main Methods:
- Fabrication and characterization of electromigrated tunnel junctions.
- Measurement of photon emission spectra and yield over a large device ensemble.
- Analysis of emission characteristics using Boltzmann statistics and plasmon-modified photonic density of states.
Main Results:
- Demonstrated a giant, material-dependent photon yield (∼10^4) in plasmonic tunnel junctions.
- Observed emission spectra consistent with a Boltzmann distribution at effective temperatures exceeding 2000 K.
- Found a linear relationship between effective temperature and applied bias, supporting a hot-carrier model.
Conclusions:
- Above-threshold light emission is significantly enhanced by hot carriers generated via nonradiative decay of localized plasmons.
- The observed phenomenon is governed by hot-carrier dynamics coupled to plasmon-modified photonic density of states.
- This research opens new avenues for applications in active photochemistry, optoelectronics, and quantum optics.
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