Infrared light emission from atomic point contacts

TL;DR

This paper demonstrates that gold atomic point contacts emit infrared radiation due to hot electron gases generated by high current densities, with the emission spectrum resembling blackbody radiation at high temperatures.

Contribution

It is the first to show infrared emission from hot electron gases in atomic point contacts, linking electron-electron interactions to photon emission in this nanoscale system.

Findings

Infrared emission observed from gold atomic point contacts.

Emission spectrum consistent with blackbody radiation at thousands of Kelvin.

Radiation intensity correlates with current and bias voltage.

Abstract

Gold atomic point contacts are prototype systems to evidence ballistic electron transport. The typical dimension of the nanojunction being smaller than the electron-phonon interaction length, even at room temperature, electrons transfer their excess energy to the lattice only far from the contact. At the contact however, favored by huge current densities, electron-electron interactions result in a nano hot electron gas acting as a source of photons. Using a home built Mechanically Controlled Break Junction, it is reported here, for the first time, that this hot electron gas also radiates in the infrared range (0.2eV to 1.2eV). Moreover, in agreement with the pioneering work of Tomchuk, we show that this radiation is compatible with a blackbody like spectrum emitted from an electron gas at temperatures of several thousands of Kelvin given by $(kB.Te)^2 = \alpha. I.V$ where $\alpha$, $I$ and $V$ are respectively a fitting parameter, the current flowing and the applied bias.