Effect of electric field on excitons in wide quantum wells

TL;DR

This study models how an external electric field influences exciton properties in wide GaAs/AlGaAs quantum wells, revealing shifts in energy, dissociation thresholds, and spectral features through numerical solutions of the Schrödinger equation.

Contribution

It introduces a microscopic model that calculates exciton behavior under electric fields in wide quantum wells, including energy shifts and dissociation thresholds.

Findings

Electric field causes a shift in exciton energy levels.

Threshold for exciton dissociation depends on well width.

Electric field induces a shift in exciton center of mass.

Abstract

A microscopic model of a heterostructure with a quantum well (QW) is proposed to study the exciton behavior in an external electric field. The effect of an electric field ranging from 0 to 6 kV/cm applied to the GaAs/AlGaAs QW structure in the growth direction is studied for several QWs of various widths up to 100 nm. The three-dimensional Schr\"odinger equation (SE) of exciton is numerically solved using the finite difference method. Wave functions and energies for several states of the heavy-hole and light-hole excitons are calculated. Dependencies of the exciton state energy, the binding energy, the radiative broadening, and the static dipole moment on the applied electric fields are determined. The threshold of exciton dissociation for the 100-nm QW is also determined. In addition, we found the electric-field-induced shift of the center of mass of the heavy-hole and light-hole exciton in the QWs. Finally, we have modeled reflection spectra of heterostructures with the GaAs/AlGaAs QWs in the electric field using the calculated energies and radiative broadenings of excitons.