Ultrafast Plasmonic Graphene Photodetector Based on the Channel Photothermoelectric Effect

We propose an ultrafast on-chip CMOS compatible graphene plasmonic photodetector based on the photothermoelectric effect (PTE) that occurs across an entire homogeneous photodetector incorporates the long-range dielectric-loaded surface plasmon polariton (LR-DLSPP) waveguide with a metal stripegraphene channel and operating beyond 500 GHz. The proposed serving simultaneously as a plasmon supporting metallic material and one of the metal electrodes. The large in-plane component of the transverse magnetic (TM) plasmonic mode can couple efficiently to the graphene causing large electron temperature increases across an entire graphene channel with a maximum located at the metal stripe edge. As a result, the electronic temperatures exceeding 6000 K at input power of only a few tens of mu W can be obtained at the telecom wavelength of 1550 nm. Even with limitations such as the melting temperature of graphene (T = 4510 K), a responsivity exceeding at least 200 A/W is achievable at a telecom wavelength of 1550 nm. It is also shown that, under certain operation conditions, the PTE channel photocurrent can be isolated from photovoltaic and p-n junction PTE contributions providing an efficient way for optimizing the overall photodetector performance.