Contribution to Excitonic Linewidth from Free Carrier-Exciton Scattering in Layered Materials: The example of h-BN

TL;DR

This paper investigates how free carrier scattering affects excitonic linewidths in monolayer h-BN, highlighting the roles of elastic and inelastic processes and their dependence on temperature and carrier density.

Contribution

It provides a detailed theoretical analysis of free carrier-exciton scattering in monolayer h-BN using variational wave functions and the Rytova--Keldysh potential, considering both elastic and inelastic transitions.

Findings

Free carrier scattering significantly broadens excitonic linewidths.

Both temperature and carrier density influence scattering contributions.

Elastic and inelastic scattering processes have distinct impacts on linewidths.

Abstract

Scattering of excitons by free carriers is a phenomena which is especially important when considering moderately to heavily doped semiconductors in low temperature experiments, where the interaction of excitons with acoustic and optical phonons is reduced. In this paper, we consider the scattering of excitons by free carriers in monolayer hexagonal Boron Nitride encapsulated by a dielectric medium. We describe the excitonic states by variational wave functions, modeling the electrostatic interaction via the Rytova--Keldysh potential. Making the distinction between elastic and inelastic scattering, the relevance of each transition between excitonic states is also considered. Finally, we discuss the contribution of free carrier scattering to the excitonic linewidth, analyzing both its temperature and carrier density dependence.