Diffusion of photoexcited carriers in graphene

TL;DR

This paper investigates how photoexcited electron-hole pairs diffuse in graphene, analyzing the transient optical response to understand diffusion regimes and elastic relaxation mechanisms, with implications for ultrafast optoelectronic applications.

Contribution

It provides a detailed theoretical description of carrier diffusion in graphene under ultrafast excitation, highlighting the impact on optical signals and relaxation processes.

Findings

Transient optical response depends on diffusion regime

Sign flip in differential transmission linked to carrier dynamics

Verification of elastic relaxation mechanisms via optical measurements

Abstract

The diffusion of electron-hole pairs, which are excited in an intrinsic graphene by the ultrashort focused laser pulse in mid-IR or visible spectral region, is described for the cases of peak-like or spread over the passive region distributions of carriers. The spatio-temporal transient optical response on a high-frequency probe beam appears to be strongly dependent on the regime of diffusion and can be used for verification of the elasic relaxation mechanism. Sign flip of the differential transmission coefficient takes place due to interplay of the carrier-induced contribution and weak dynamic conductivity of undoped graphene.