Giant Photoresponsivity of Midinfrared Hyperbolic Metamaterials in the Photon-Assisted-Tunneling Regime

We explore broadband and omnidirectional midinfrared rectification based on nanopatterned hyperbolic metamaterials, composed of two dissimilar metals separated by an ultrathin dielectric layer. The exotic slow-light modes supported by such periodically trenched hyperbolic metamaterials efficiently trap incident radiation in massively parallel metal-insulator-metal tunnel junctions producing ultrafast infrared rectification via photon-assisted tunneling. This leads to a highly efficient photon-to-electron transduction with obtained photocurrent orders of magnitude larger than conventional lumped-element devices, such as nanorectennas and point-contact rectifiers. Our results promise an impact on infrared energy harvesters and plasmonic photodetectors.