# Spatio-temporal dynamics in graphene

## TL;DR

This paper investigates the spatio-temporal dynamics of optically excited carriers in graphene, revealing the diffusion coefficient and the effects of scattering processes on carrier diffusion, which are crucial for optoelectronic applications.

## Contribution

It provides a microscopic, space- and time-resolved analysis of carrier diffusion in graphene, including the impact of phonon and carrier-carrier scattering.

## Key findings

- Diffusion coefficient D ≈ 360 cm²/s
- Carrier-phonon and carrier-carrier scattering significantly influence diffusion
- Phonon-induced back-diffusion counteracts spatial broadening

## Abstract

Temporally and spectrally resolved dynamics of optically excited carriers in graphene has been intensively studied theoretically and experimentally, whereas carrier diffusion in space has attracted much less attention. Understanding the spatio-temporal carrier dynamics is of key importance for optoelectronic applications, where carrier transport phenomena play an important role. In this work, we provide a microscopic access to the time-, momentum-, and space-resolved dynamics of carriers in graphene. We determine the diffusion coefficient to be $D \approx 360$cm$^{2}$/s and reveal the impact of carrier-phonon and carrier-carrier scattering on the diffusion process. In particular, we show that phonon-induced scattering across the Dirac cone gives rise to back-diffusion counteracting the spatial broadening of the carrier distribution.