Direct and indirect exciton mixture in double quantum wells

TL;DR

This paper investigates the behavior of excitons in double quantum wells, revealing how high pumping can induce a mixed phase of direct and indirect excitons, explaining recent experimental observations.

Contribution

It introduces the concept of a mixed direct-indirect exciton phase in double quantum wells and provides a theoretical estimate of exciton energies in this phase.

Findings

High pumping can equalize direct and indirect exciton energies.

A mixed exciton phase can form at high excitation levels.

The model explains puzzling features in recent experiments.

Abstract

The exciton system in double quantum well is considered under condition when the ground state is the spatially indirect exciton. At high pumping growth of the exciton concentration can lead to so significant increase of the indirect exciton energy that becomes equal to the direct exciton energy. Then further increase of pumping leads to formation of mixed direct - indirect exciton phase. A rough estimate of the exciton energy in the mixed phase explains puzzling features of some recent exciton measurements. An experiment that would reveal main characteristic features of the mixed phase is suggested.