Collective Properties of Excitons in Presence of a Two-Dimensional Electron Gas

TL;DR

This paper investigates the collective behaviors of 2D excitons in quantum wells with a 2D electron gas, revealing how exciton density and inter-well separation influence superfluidity and phase transition temperatures, indicating potential for long-range exciton transport.

Contribution

It provides new insights into how a 2DEG affects the superfluid properties and phase transitions of 2D excitons and dipole excitons in quantum well systems.

Findings

K-T transition temperature increases with exciton density.

Superfluid density rises with inter-well separation.

Long-range exciton transport becomes feasible at higher densities.

Abstract

We have studied the collective properties of two-dimensional (2D) excitons immersed within a quantum well which contains 2D excitons and a two-dimensional electron gas (2DEG). We have also analyzed the excitations for a system of 2D dipole excitons with spatially separated electrons and holes in a pair of quantum wells (CQWs) when one of the wells contains a 2DEG. Calculations of the superfluid density and the Kosterlitz-Thouless (K-T) phase transition temperature for the 2DEG-exciton system in a quantum well have shown that the K-T transition temperature increases with increasing exciton density and that it might be possible to have fast long range transport of excitons. The superfluid density and the K-T transition temperature for dipole excitons in CQWs in the presence of a 2DEG in one of the wells increases with increasing inter-well separation.