Exciton effective mass enhancement in coupled quantum wells in electric and magnetic fields

TL;DR

This paper investigates how electric and magnetic fields influence exciton states in coupled quantum wells, revealing a non-monotonous effective mass dependence on magnetic field and providing detailed spectral and physical property mappings.

Contribution

It introduces a comprehensive real-space three-dimensional calculation of exciton states in CQWs under external fields, including exciton mass renormalization and spectral analysis.

Findings

Exciton effective mass shows non-monotonous dependence on magnetic field.

Electric and magnetic fields significantly alter exciton absorption spectra.

Ground state properties like Bohr radius and binding energy are quantitatively characterized.

Abstract

We present a calculation of exciton states in semiconductor coupled quantum wells (CQWs) in the presence of electric and magnetic fields applied perpendicular to the QW plane. The exciton Schr\"odinger equation is solved in real space in three dimensions to obtain the Landau levels of both direct and indirect excitons. Calculation of the exciton energy levels and oscillator strengths enables mapping of the electric and magnetic field dependence of the exciton absorption spectrum. For the ground state of the system, we evaluate the Bohr radius, optical lifetime, binding energy and dipole moment. The exciton mass renormalization due to the magnetic field is calculated using a perturbative approach. We predict a non-monotonous dependence of the exciton ground state effective mass on magnetic field. Such a trend is explained in a classical picture, in terms of the ground state tending from an indirect to a direct exciton with increasing magnetic field.