Photo-thermoelectric Current Enhancement in Graphene-Based Photodetectors Using Plasmonic Nanostructures

Abstract

A promising way to enhance channel absorption in graphene-based photodetectors is using plasmonic nanostructures. Here, we show that by using metallic nano-gratings on top of the electrodes, an asymmetric hot carrier temperature profile with high intensity along the graphene channel is created. We show that this asymmetric profile creates a photo-thermoelectric (PTE) current even with scenarios like similar contacts materials and uniform Seebeck coefficient along the channel. Our analytical calculations reveal that in the case of normal beam illumination and applying source-drain voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> ), the calculated PTE current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TEP</sub> ) increases considerably. Due to enhanced instructive coupling between plasmonic absorption modes originating from contacts and absorption modes in the channel itself, the proposed photodetector exhibits a maximum responsivity of R = ≈ 800 V/W related to absorbed power.