A Graphene Terahertz Detector based on the Photo-Thermoelectric Effect with Frequency Selectivity

We design a fast room-temperature terahertz detector based on the photo-thermoelectric effect. Our device takes full advantage of a novel approach to enhance the responsibility and coupling of the terahertz wave to the detector. High-performance photodetection was achieved by combining the localized surface plasmon resonance of dual grating gates with the resonant modes of a Fabry-Perot cavity configuration. This hybrid structure benefits from the near-perfect absorptance of graphene, owing to the strong interaction between terahertz radiation and the graphene layer. This notable absorption leads to an amplified thermal gradient across the graphene channel due to localized heat generation from terahertz wave absorption. In addition, dual grating gates are adopted to form a pn-junction, allowing for a non-uniform Seebeck coefficient along the channel, which provides a higher generated voltage. The simulation results indicate under the low gate voltages of +/- 0.2 V, the detector demonstrates a responsivity of 1.15 V/W and a noise-equivalent power (NEP) of nW/root Hz at the frequency of 1.55 THz.