Broadband electromagnetic response and ultrafast dynamics of few-layer epitaxial graphene

TL;DR

This study investigates the broadband optical properties and ultrafast carrier dynamics of few-layer epitaxial graphene, revealing significant terahertz and near-infrared absorption and a characteristic recombination time of 1.2 ps.

Contribution

It provides new insights into the optical conductivity and ultrafast carrier behavior of epitaxial graphene in the few-layer limit, combining experimental spectra with dynamic measurements.

Findings

Significant terahertz and near-infrared absorption in few-layer graphene

Dominance of excess hole carriers in non-equilibrium terahertz transmission

Recombination time of 1.2 ps for minority carriers

Abstract

We study the broadband optical conductivity and ultrafast carrier dynamics of epitaxial graphene in the few-layer limit. Equilibrium spectra of nominally buffer, monolayer, and multilayer graphene exhibit significant terahertz and near-infrared absorption, consistent with a model of intra- and interband transitions in a dense Dirac electron plasma. Non-equilibrium terahertz transmission changes after photoexcitation are shown to be dominated by excess hole carriers, with a 1.2-ps mono-exponential decay that reflects the minority-carrier recombination time.