# Tight-binding terahertz plasmons in chemical vapor deposited graphene

## TL;DR

This study demonstrates the experimental observation of terahertz plasmons in CVD graphene structures with metal gratings, revealing their potential for large-area terahertz detectors despite low carrier mobility.

## Contribution

First experimental evidence of terahertz plasmons in CVD graphene with metal gratings, showing their resonance characteristics and implications for terahertz detection.

## Key findings

- Plasmon resonance observed in 5-10 THz range in CVD graphene.
- Plasmon lifetime is weakly affected by grain boundaries and defects.
- Resonant frequency depends on stripe width, not grating period.

## Abstract

Transistor structures comprising graphene and sub-wavelength metal gratings hold a great promise for plasmon-enhanced terahertz detection. Despite considerable theoretical effort, little experimental evidence for terahertz plasmons in such structures was found so far. Here, we report an experimental study of plasmons in graphene-insulator-grating structures using Fourier transform spectroscopy in 5-10 THz range. The plasmon resonance is clearly visible above the Drude absorption background even in chemical vapor deposited (CVD) graphene with low carrier mobility $\sim 10^3$ cm$^2$/(V s). We argue that plasmon lifetime is weakly sensistive to scattering by grain boundaries and macoscopic defects which limits the mobility of CVD samples. Upon placing the grating in close proximity to graphene, the plasmon field becomes tightly bound below the metal stripes, while the resonant frequency is determined by the stripe width but not by grating period. Our results open the prospects of large-area commercially available graphene for resonant terahertz detectors.