Large scale tunneling junctions for electrically driven plasmonics

This work focuses on the fabrication of light emitting tunneling junctions in planar configuration comprised of thin-film material stacks analog to metal-insulator-semiconductor plate capacitors. Electrical and structural properties are studied by different experimental techniques (current-voltage analysis, impedance spectroscopy) and compared to existing theories. Assessment of the junction quality is done in comparison to known features of electrically-driven plasmons, such as the bias dependent cut-off frequency, the dependency of the emission intensity on the tunneling current and tuneability of the spectra by implementation of different materials. Enhanced scattering and tuneability of light emission features from tunneling junctions by adsorption of chemically-synthesized nanoparticles is demonstrated and localization of the emission hot spots by correlation with measurements in external illumination and topography scans are discussed. Operational stability is increased by decoupling of the fabrication sub-steps, i.e. deposition of high quality thin-film stacks and chemical synthesis of particles with tailored optical properties. The role of nanoparticle geometry and material as hot spots in light emitting tunneling junctions is described and distinguished to reference experiments with external illumination. Emission instabilities in low-frequency regimes from hot spots with uncorrelated phases have been observed and are discussed. Potential transferability of electrically-driven plasmons to established detection schemes is demonstrated exemplary by mimicking a study of a plasmonic nanoruler. Additionally, a first proof-of-principle study on the emission from light emitting tunneling junctions in direct water immersion is described.



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