Graphene Plasmonic Fractal Metamaterials for Broadband Photodetectors

• Published in: arXiv.org 2020-05
• Main Authors: De Nicola, Francesco, Nikhil Santh Puthiya Purayil, Miŝeikis, Vaidotas, Spirito, Davide, Tomadin, Andrea, Coletti, Camilla, Polini, Marco, Krahne, Roman, Pellegrini, Vittorio
• Format: Article
• Language: English
• Subjects: Broadband; Chemical sensors; Electromagnetic absorption; Electromagnetic fields; Fractals; Graphene; Metamaterials; Optoelectronic devices; Photometers; Plasmonics; Plasmons; Quantum efficiency; Room temperature; Self-similarity; Upper bounds
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2005.06567

Metamaterials have recently established a new paradigm for enhanced light absorption in state-of-the-art photodetectors. Here, we demonstrate broadband, highly efficient, polarization-insensitive, and gate-tunable photodetection at room temperature in a novel metadevice based on gold/graphene Sierpinski carpet plasmonic fractals. We observed an unprecedented internal quantum efficiency up to 100% from the near-infrared to the visible range with an upper bound of optical detectivity of \(10^{11}\) Jones and a gain up to \(10^{6}\), which is a fingerprint of multiple hot carriers photogenerated in graphene. Also, we show a 100-fold enhanced photodetection due to highly focused (up to a record factor of \(|E/E_{0}|\approx20\) for graphene) electromagnetic fields induced by electrically tunable multimodal plasmons, spatially localized in self-similar fashion on the metasurface. Our findings give direct insight into the physical processes governing graphene plasmonic fractal metamaterials. The proposed structure represents a promising route for the realization of a broadband, compact, and active platform for future optoelectronic devices including multiband bio/chemical and light sensors.