Abstract
In this work, we present a detailed analysis of the interplay of Coulomb effects and different mechanisms that can lead to carrier-localization effects in -plane quantum wells. As mechanisms for carrier localization, we consider here effects introduced by random alloy fluctuations as well as structural inhomogeneities such as well-width fluctuations. Special attention is paid to the impact of the well width on the results. All calculations have been carried out in the framework of atomistic tight-binding theory. Our theoretical investigations show that independent of the well widths studied here, carrier-localization effects due to built-in fields, well-width fluctuations, and random-alloy fluctuations dominate over Coulomb effects in terms of charge-density redistributions. However, the situation is less clear cut when the well-width fluctuations are absent. For a large well width (approximately ), charge-density redistributions are possible, but the electronic and optical properties are basically dominated by the out-of-plane carrier separation originating from the electrostatic built-in field. The situation changes for lower well widths (), where the Coulomb effect can lead to significant charge-density redistributions and, thus, might compensate for a large fraction of the spatial in-plane wave-function separation observed in a single-particle picture. Given that this in-plane separation has been regarded as one of the main drivers behind the green gap problem, our calculations indicate that radiative recombination rates might significantly benefit from a reduced quantum-well-barrier-interface roughness.
5 More- Received 17 April 2018
- Revised 10 July 2018
DOI:https://doi.org/10.1103/PhysRevApplied.10.034027
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