# Transient response under ultrafast interband excitation of an intrinsic graphene

## TL;DR

This paper theoretically investigates the ultrafast transient carrier dynamics in intrinsic graphene under interband excitation, analyzing energy relaxation, generation-recombination processes, and their effects on optical and electrical responses.

## Contribution

It provides a detailed theoretical analysis of carrier distributions and transient responses in graphene during ultrafast excitation, considering different scattering regimes.

## Key findings

- Transient optical response depends on relaxation and recombination dynamics.
- Carrier distributions vary significantly between negligible and dominant intercarrier scattering.
- Energy relaxation involves quasielastic acoustic phonon scattering and thermal radiation processes.

## Abstract

The transient evolution of carriers in an intrinsic graphene under ultrafast excitation, which is caused by the collisionless interband transitions, is studied theoretically. The energy relaxation due to the quasielastic acoustic phonon scattering and the interband generation-recombination transitions due to thermal radiation are analyzed. The distributions of carriers are obtained for the limiting cases when carrier-carrier scattering is negligible and when the intercarrier scattering imposes the quasiequilibrium distribution. The transient optical response (differential reflectivity and transmissivity) on a probe radiation and transient photoconductivity (response on a weak dc field) appears to be strongly dependent on the relaxation and recombination dynamics of carriers.