Design and analysis of bi-layer graphene based photodetector enhanced by metallic nano-antenna

A new design of graphene-based photodetectors is proposed and studied to be used in near and mid-IR applications. To do so, a bi-layer graphene is implemented as active photo-absorbing region and its absorption spectra was calculated. Based on its response peak, an array of metallic nano rods is designed to be inserted between two layers of graphene and resonate in desired response wavelengths. Such a resonance causes induction and enhancement of incident field in the upper and lower graphene layers and leads to increased absorption. The results show that by using the nano-rods, the mid-IR absorption response of graphene bi-layer is doubled around 6.8 μm, however it is polarization-dependent. We also studied performance characteristics of device such as photo-responsivity, dark and photocurrent and specific detectivity. According the calculations, the proposed photodetector exhibits responsivity as high as about 27 A/W which is higher than previously reported works.