Terahertz Electronic Metadevices: Principles behind the Ultra-high Cutoff Frequency

The propagation of different slow-wave modes in the metal-insulator-2DEG (Mi2DEG) structures-a process unique to electronic metadevices-induces a pronounced current confinement within the device's active region. This confinement significantly enhances the device's modulation capability, resulting in a substantial increase in the cutoff frequency. Here, we elucidate this phenomenon through numerical simulations and validate experimentally across a broad frequency range, from near DC to THz. Metadevices fabricated on InAlN/GaN on SiC exhibited ultra-low contact and total resistances, reaching 30 Ωµm and 100 Ωµm, respectively. As a result, a tenfold increase in the device cutoff frequency, approaching 20 THz, was achieved along with a high on-off ratio above 10 at 0.75 THz. This work advances the fundamental understanding of the physical processes in electronic metadevices, paving the way for future THz electronic technologies.