Kinetics of the inner ring in the exciton emission pattern in GaAs coupled quantum wells

TL;DR

This paper investigates the formation and disappearance dynamics of the inner exciton emission ring in GaAs coupled quantum wells, revealing rapid cooling and transport processes with specific formation and decay times.

Contribution

It provides detailed measurements of the formation and decay times of the inner ring, and explains these phenomena through exciton transport and cooling mechanisms.

Findings

Inner ring forms in about 30 ns after laser excitation

Inner ring disappears within 4 ns after laser is turned off

Excitons outside the laser region are cooled efficiently during excitation

Abstract

We report on the kinetics of the inner ring in the exciton emission pattern. The formation time of the inner ring following the onset of the laser excitation is found to be about 30 ns. The inner ring was also found to disappear within 4 ns after the laser termination. The latter process is accompanied by a jump in the photoluminescence (PL) intensity. The spatial dependence of the PL-jump indicates that the excitons outside of the region of laser excitation, including the inner ring region, are efficiently cooled to the lattice temperature even during the laser excitation. The ring formation and disappearance are explained in terms of exciton transport and cooling.