Stability of optically-active charged excitons in quasi-two dimensional systems

TL;DR

This paper investigates the stability of negatively charged excitons in quasi-two-dimensional systems under magnetic fields, providing a detailed numerical analysis that explains experimental observations and highlights effects beyond simple approximations.

Contribution

It offers an exact numerical solution for charged excitons in various geometries, revealing the importance of charge distribution in their stability and optical properties.

Findings

Charge distribution influences exciton stability and photoluminescence.

The theory explains recent experimental results in GaAs quantum wells.

Effects beyond the lowest Landau level approximation are significant.

Abstract

A negatively charged quasi-two dimensional exciton ($X^-$) is solved exactly numerically in the presence of a uniform perpendicular B-field. Various quasi-two dimensional geometries are studied. The charge distribution of the $X^-$ parallel to the B-field is found to be crucial in determining the stability of the optically-active $X^-$ and hence its photoluminescence (PL) signature. The theory provides a quantitative explanation of recent experimental results obtained for a GaAs quantum well. Effects are found which cannot be described within a lowest Landau level approximation. PACS: 78.20.Ls 78.66.-w 73.20.Dx