Abstract
In this work, a theoretical study of the electronic and the optical properties of a new family of strain-free GaAs/AlGaAs quantum dots (QDs) obtained by AlGaAs nanohole filling is presented. The considered model consists of solving the three-dimensional effective-mass Schrödinger equation, thus providing a complete description of the neutral and charged complex excitons’ fine structure. The QD size effect on carrier confinement energies, wave functions, and s-p splitting is studied. The direct Coulomb interaction impact on the calculated s and p states’ transition energies is investigated. The behaviour of the binding energy of neutral and charged excitons (X− and X+) and biexciton XX versus QD height is studied. The addition of the correlation effect allows to explain the nature of biexcitons often observed experimentally.
Highlights
Optimizing the optical qualities of quantum dots (QDs) remains a challenge for researchers
We provide a modelling of the GaAs/ AlGaAs QDs’ shape reported by Heyn et al [2], compatible with available atomic force microscopy (AFM) images. e theoretical study in this paper will focus on the dependence of the confinement energy of the carriers, for the ground state s and state p, on the QD height. e calculations are performed by adapting a simple configuration based on BenDaniel and Duke, Hamiltonian [6], which requires much computation time. e obtained results will be compared to the literature experimental results for validation
In the literature, unstrained self-assembled QDs have been modelled by different shapes such as cone [7, 8], pyramid with a square base [9, 10], and lens [11, 12]. e electronic structure of QDs has been calculated by adopting various approaches such as the pseudo-potential model proposed by Williamson and Zunger [13, 14], the strong bond model suggested by Lee et al [15], and the formalism of the envelope function at several bands by Stier et al [16]
Summary
A theoretical study of the electronic and the optical properties of a new family of strain-free GaAs/AlGaAs quantum dots (QDs) obtained by AlGaAs nanohole filling is presented. E considered model consists of solving the three-dimensional effective-mass Schrodinger equation, providing a complete description of the neutral and charged complex excitons’ fine structure. E QD size effect on carrier confinement energies, wave functions, and s-p splitting is studied. E direct Coulomb interaction impact on the calculated s and p states’ transition energies is investigated. E behaviour of the binding energy of neutral and charged excitons (X− and X+) and biexciton XX versus QD height is studied. E addition of the correlation effect allows to explain the nature of biexcitons often observed experimentally
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