Antenna-coupled photon emission from hexagonal boron nitride tunnel junctions

• Published in: Nature nanotechnology Vol. 10; no. 12; pp. 1058 - 1063
• Main Authors: Parzefall, M., Bharadwaj, P., Jain, A., Taniguchi, T., Watanabe, K., Novotny, L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-12-2015; Nature Publishing Group
• Subjects: 140/125; 142/126; 147/136; 639/624/399/1015; 639/925/927/1021; Antennas; Boron; Boron nitride; Conversion; Data processing; Electrodes; Electromagnetic fields; Electrons; Gold; Lasers; Light; Materials Science; Nanostructure; Nanotechnology; Nanotechnology and Microengineering; Optical properties; Radiation; Semiconductors; Signal processing; Slot antennas; Tunnel junctions
• ISSN: 1748-3387; 1748-3395
• DOI: 10.1038/nnano.2015.203

The ultrafast conversion of electrical signals to optical signals at the nanoscale is of fundamental interest for data processing, telecommunication and optical interconnects. However, the modulation bandwidths of semiconductor light-emitting diodes are limited by the spontaneous recombination rate of electron–hole pairs, and the footprint of electrically driven ultrafast lasers is too large for practical on-chip integration. A metal–insulator–metal tunnel junction approaches the ultimate size limit of electronic devices and its operating speed is fundamentally limited only by the tunnelling time. Here, we study the conversion of electrons (localized in vertical gold–hexagonal boron nitride–gold tunnel junctions) to free-space photons, mediated by resonant slot antennas. Optical antennas efficiently bridge the size mismatch between nanoscale volumes and far-field radiation and strongly enhance the electron–photon conversion efficiency. We achieve polarized, directional and resonantly enhanced light emission from inelastic electron tunnelling and establish a novel platform for studying the interaction of electrons with strongly localized electromagnetic fields.
Efficient conversion of electrical current to photon emission can be acheived in a tunnelling device coupled to a nanostructured optical antenna.