Plasmon-enhanced graphene photodetector with CMOS-compatible titanium nitride

TL;DR

This paper presents a CMOS-compatible, plasmon-enhanced graphene photodetector using titanium nitride, achieving high responsivity, ultra-fast bandwidth over 100 GHz, and a compact footprint for on-chip optical detection.

Contribution

It introduces a novel plasmonic graphene photodetector with titanium nitride, combining high responsivity, ultra-fast operation, and CMOS compatibility, surpassing previous device footprints.

Findings

Responsivity up to 1.4 A/W at 3.5 μm length

Bandwidth exceeds 100 GHz

Ultra-low noise equivalent power (<25 pW/√Hz)

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 $\sim$2.3% of light. Plasmonic metals can enhance the responsivity of graphene photodetectors, but may result in CMOS-incompatible devices, depending on the choice of metal. Here, we propose a plasmon-enhanced photothermoelectric graphene detector using CMOS-compatible titanium nitride (TiN) on the silicon-on-insulator (SOI) platform. The device performance is quantified by its responsivity, operation speed, and noise equivalent power. Its bandwidth exceeds 100$\,$GHz, and it exhibits a nearly flat photoresponse across the telecom C-band. The photodetector responsivity is as high as 1.4$\,$A/W (1.1$\,$A/W external) at an ultra-compact length of 3.5$\,\mu$m, which is the most compact footprint reported for a graphene-based waveguide photodetector. Furthermore, it operates at zero-bias, consumes zero energy, and has an ultra-low intrinsic noise equivalent power (NEP$\,$<$\,25\:\text{pW/}\sqrt{\text{Hz}}$)