Band alignment transition from type I to type II in GaAs / AlxGa1-x As quantum ring
Section snippets
Author contribution
Rihab Sellami: Investigation, Writing - original draft, Visualization, Afef Ben Mansour and Mohamed Souhail Kehili: Writing, Adnen Melliti: Conceptualization, Methodology, Validation, Supervision.
Theoretical model
The height of the studied GaAs/AlGaAs QR as a function of the polar coordinates is modeled by the expression proposed by Fomin et al. [18]:Where R is the radius of the rim top, ho is the height at the center (i.e. r = 0), is the height away from the ring, and hM is the rim height; and determine the inner and outer slope of the rim, respectively.
To have a QR structure similar to the AFM experimental results
Electronic energy and wavefunction
The composition in real GaAs/AlxGa1-xAs nanostructures grown by droplet epitaxy is not uniform. The Al composition (x) varies from the WL to the tip of the nanostructure [21,22]. However, to simplify the calculation, we supposed a uniform composition profile inside the QR and in the barrier.
In Fig. 2, Fig. 3, we present the hole and electron wavefunctions for different Al-concentration (x) and rim height (hM) respectively.
We notice from Fig. 2 that the hole is confined inside the QR and the
Conclusion
In this paper we studied theoretically the electronic and optical properties of carriers in a QR GaAs/AlxGa1-x As and the transition of band alignment for type I to type II. The investigation is done by calculating the wavefunctions and energies of electron and hole using the effective mass approximation with variation in Al-composition and the rim height. We showed that the localization of electrons and holes wavefunction is sensitive to the variation of x and hM.
The increase of x allows the
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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