Compact Graphene Plasmonic Slot Photodetector on Silicon-on-insulator with High Responsivity

Graphene has extraordinary electro-optic properties and is therefore a promising candidate for monolithic photonic devices such as photodetectors. However, the integration of this atom-thin layer material with bulky photonic components usually results in a weak light-graphene interaction leading to large device lengths, limiting electro-optic performance. In contrast, here we demonstrate a plasmonic slot graphene photodetector on silicon-on-insulator platform with high responsivity of 0.7 A/W given a just 5 µm-short device length. We observe that the maximum photocurrent, and hence the highest responsivity, scales inversely with the slot width. Using a dual-lithography step, we realize 15 nm narrow slots that show a 30-times higher responsivity per unit device-length compared to photonic graphene photodetectors. Furthermore, we reveal that the back-gated electrostatics is overshadowed by channel-doping contributions induced by the contacts of this ultra-short channel graphene photodetector. This leads to ...