Probing electronic lifetimes and phonon anharmonicities in high-quality chemical vapor deposited graphene by magneto-Raman spectroscopy

TL;DR

This study uses magneto-Raman spectroscopy to analyze high-quality CVD graphene, revealing insights into electronic lifetimes and phonon anharmonicities, demonstrating the material's exceptional electronic quality and behavior under varying laser powers.

Contribution

It provides the first detailed magneto-Raman analysis of CVD graphene encapsulated in hBN, quantifying electronic and phononic lifetimes and anharmonic effects.

Findings

High electronic quality with minimal LL decay width of 140 1/cm at low power

LL decay width increases with laser power, saturating at 18 fs lifetime

Structural quality comparable to exfoliated graphene

Abstract

We present a magneto-Raman study on high-quality single-layer graphene grown by chemical vapor deposition (CVD) that is fully encapsulated in hexagonal boron nitride by a dry transfer technique. By analyzing the Raman D, G, and 2D peaks, we find that the structural quality of the samples is comparable to state-of-the-art exfoliated graphene flakes. From B field dependent Raman measurements, we extract the broadening and associated lifetime of the G peak due to anharmonic effects. Furthermore, we determine the decay width and lifetime of Landau level (LL) transitions from magneto-phonon resonances as a function of laser power. At low laser power, we find a minimal decay width of 140 1/cm highlighting the high electronic quality of the CVD-grown graphene. At higher laser power, we observe an increase of the LL decay width leading to a saturation with the corresponding lifetime saturating at a minimal value of 18 fs.