Researchers from Harutyunyan Lab and their collaborators have built an ultrathin electronic device that can both make and sense light at the scale of a few atoms. The heart of the device is a remarkably stable tunnel junction, two metal films separated by a crystal-clear layer of lutetium oxide (Lu₂O₃). In this tiny gap, electrons don’t flow the usual way; they “tunnel,” a quantum shortcut that lets signals switch at extreme speeds and low power. By carefully shaping this junction, the team shows they can generate light, detect it, and convert light into electrical signals in the same nanoscale platform, opening a route to faster, smaller, and more energy-efficient photonic chips.
Beyond the engineering feat, the study also explains how the light and current arise. The authors disentangle three key effects: optical rectification (turning light into DC current), hot-electron transport (swift carriers launched by light), and thermal tunneling (heat-driven currents), and show how each can be dialed up or down on demand. That level of control turns the junction into a “Swiss Army knife” for nanophotonics: a single, durable component that can serve as a tiny light source, detector, or signal mixer. In the long run, such devices could help shrink data-center optics onto chips, boost on-device sensing (from chemical fingerprints to biomedical signals), and enable ultrafast, low-energy communications in everyday electronics.
This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award # DE-SC0020101, and was recently published in the journal ACS Nano: https://pubs.acs.org/doi/10.1021/acsnano.5c03217