On the radiative lifetime of free-moving two-dimensional excitons

TL;DR

This paper proposes a microscopic explanation for how the radiative lifetime of free-moving 2D excitons depends linearly on their temperature, identifying a temperature where the lifetime is minimized and discussing agreement with prior results.

Contribution

It introduces a simple microscopic model explaining the temperature dependence of exciton radiative lifetime, highlighting a characteristic temperature where the lifetime is shortest.

Findings

Radiative lifetime depends linearly on temperature.

Existence of a characteristic temperature (~Kelvin range) with minimal lifetime.

Agreement with previous theoretical and experimental observations.

Abstract

A simple microscopic mechanism explaining the linear dependence of the radiative lifetime of free-moving two-dimensional excitons on their effective temperature is suggested. It is shown that there exists a characteristic effective temperature (of about few Kelvin) defined by the exciton-acoustic phonon interaction at which the radiative lifetime is minimal. Below this temperature the lifetime starts to increase with decreasing temperature. The correspondence with previous theoretical and experimental results is discussed.