Plasmonic graphene photodetector based on channel photo-thermoelectric effect

We propose an on-chip CMOS compatible graphene plasmonic photodetector based on the photo-thermoelectric effect (PTE) that occurs across an entire homogeneous graphene channel. The proposed photodetector incorporates the long-range dielectric-loaded surface plasmon polariton (LR-DLSPP) waveguide with a metal stripe serving simultaneously as a plasmon supporting metallic material and one of the metal electrodes. Large in-plane component of the transverse magnetic (TM) plasmonic mode can couple efficiently to the graphene causing large temperature increases across an entire graphene channel with a maximum located at the metal stripe edge. As a result, the electronic temperatures exceeding 12000K at input power of only a few tens of μW can be obtained at the telecom wavelength of 1550nm. Even with limitations such as the melting temperature of graphene (T= 4510 K), a responsivity exceeding at least 200 A/W is achievable at 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.

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