Hot-Carrier Enhanced Light Emission: The Origin Of Above-Threshold Photons From Electrically Driven Plasmonic Tunnel Junctions

Understanding the origin of above-threshold photons emitted from electrically driven tunnel junctions (omega > eV b withV b being the applied voltage bias) is of current interest in nano-optics and holds great promise to create novel on-chip optoelectronic and energy conversion technologies. Here, we report experimental observation and theoretical analysis of above-threshold light emission from electromigrated Au tunnel junctions. We compare our proposed hot-carrier enhanced light emission theory with existing models, including blackbody thermal radiation, multi-electron interactions, and an interpretation involving finite temperature effects. Our study highlights the key role of plasmon-induced hot carrier dynamics in emitting above-threshold photons and the need to further explore the underlying mechanisms and optimization of upconversion effects in plasmonically active nanostructures.