Hue Do1,2,Lin Wu3,2,Michel Bosman1,2
National University of Singapore1,Agency for Science, Technology and Research2,Singapore University of Technology and Design3
Hue Do1,2,Lin Wu3,2,Michel Bosman1,2
National University of Singapore1,Agency for Science, Technology and Research2,Singapore University of Technology and Design3
Geometric diodes exhibit current rectification by preferential scattering of quasi-ballistic electrons in designed resonator geometries. High rectification ratios at room temperature have been shown in graphene <sup>[1]</sup> and recently also in silicon geometric diodes <sup>[2]</sup>, which enables energy harvesting from radiation in the THz and GHz domains. In this work, we present rectification in plasmonic resonators operating in the near-IR frequency range. We use Particle-in-cell simulations <sup>[3][4]</sup> that solve the full-wave Maxwell equations while also considering the electron dynamics at the resonator boundaries that result in preferential scattering. Our approach reveals AC rectifying behaviour of such geometric diodes, which was not possible in earlier analytical models <sup>[1][2]</sup>. We demonstrate up to 1.7 asymmetry ratio between the current density in forward and backward direction for resonators that are locally excited by fast-moving electrons; and significant charge accumulation upon continuous-wave laser illumination. Following these theoretical predictions, we have fabricated TEM samples of our designed geometric diodes and by using nano-optical spectroscopy in the TEM, we experimentally confirm our predictions. This work will open opportunities for energy harvesting from near IR radiation and surface plasmon polariton rectification in plasmonic circuits.<br/><br/>[1] Zhu, Z., Joshi, S., Grover, S. and Moddel, G., 2013. Graphene geometric diodes for terahertz rectennas. Journal of Physics D: Applied Physics, 46(18), p.185101.<br/>[2] Custer, J.P., Low, J.D., Hill, D.J., Teitsworth, T.S., Christesen, J.D., McKinney, C.J., McBride, J.R., Brooke, M.A., Warren, S.C. and Cahoon, J.F., 2020. Ratcheting quasi-ballistic electrons in silicon geometric diodes at room temperature. Science, 368(6487), pp.177-180.<br/>[3] Ding, W. J., Lim, J. Z. J, Do., T. B. H. , Xiong, X., Mahfoud, Z., Png, C. E., Bosman, M., Ang, L. K., and Wu, L., 2020. Particle simulation of plasmons. Nanophotonics 9(10), 3303–3313.<br/>[4] Do., T. B. H., Ding, W. J., Mahfoud, Z., Wu, L., and Bosman, M., 2021. Electron dynamics in plasmons. Nanoscale 13, 2801.