Electronic and optical properties of charge carriers in a GaSb quantum ring in a GaAs/Al0.6Ga0.4As quantum well

Abstract

We present a study of the electronic and optical properties of charge carriers in a GaSb quantum ring inside a GaAs/Al0.6Ga0.4As quantum well as a function of the well width. After calculating the strain field using the continuum elasticity model, we analyzed the changes in the wavefunctions and energies of electron and hole with and without Coulomb interaction, using the effective mass approximation. The exciton total energy and binding energy, as well as the oscillator strength and radiative lifetime, are also examined as a function of the quantum well width. An interplay between the Coulomb interaction and the confinement effect was found, whereby the Coulomb effects are more important for wide quantum wells and the confinement effect becomes dominant for narrow ones—especially for 5 nm quantum wells, where a drastic change of the wavefunction accompanied by an increase of the exciton lifetime and transition energy was observed. A good agreement with the experimental results of Hodgson et al [2016 J. Appl. Phys. 119, 044305] was found for narrow quantum wells. For wide wells, however, our results differed from Hodgson’s results. This is attributed to the weak Coulomb effect induced by the single electron–hole pair in our calculations instead of the multiple-pair case in Hodgson’s results.