Plasmon-enhanced graphene photodetector with CMOS-compatible titanium nitride

Abstract

Graphene has emerged as an ultrafast optoelectronic material for on-chip photodetector applications. The 2D nature of graphene enables its facile integration with complementary metal–oxide semiconductor (CMOS) microelectronics and silicon photonics, yet graphene absorbs only ∼ 2.3 % of light. Plasmonic metals can enhance the responsivity of graphene photodetectors, but may result in CMOS-incompatible devices, depending on the choice of metal. Here we propose a plasmon-enhanced photothermoelectric graphene detector using CMOS-compatible titanium nitride on the silicon-on-insulator platform. The device performance is quantified by its responsivity, operation speed, and noise equivalent power. Its bandwidth exceeds 100 GHz, and it exhibits a nearly flat photoresponse across the telecom C-band. The photodetector responsivity is as high as 1.4 A/W (1.1 A/W external) at an ultra-compact length of 3.5 µm, which is the most compact footprint reported for a graphene-based waveguide photodetector. Furthermore, it operates at zero-bias, consumes zero energy, and has an ultra-low intrinsic noise equivalent power ( N E P < 20 p W / H z ).