Impact of alloy fluctuations and Coulomb effects on the electronic and optical properties of c-plane GaN/AlGaN quantum wells

Leontiadou, MA; Roble, AA; Patra, SK; Massabau, F; Fentrup, M; Dawson, P; Kappers, MJ; Oliver, RA; Graham, DM; Schulz, S

Abstract

We report on a combined theoretical and experimental study of the impact of alloy fluctuations and Coulomb effects on the
electronic and optical properties of c-plane GaN/AlGaN multi-quantum well systems. The presence of carrier localization
effects in this system was demonstrated by experimental observations, such as the “S-shape” temperature dependence of
the photoluminescence (PL) peak energy, and non-exponential PL decay curves that varied across the PL spectra at 10 K. A
three-dimensional modified continuum model, coupled with a self-consistent Hartree scheme, was employed to gain insight into
the electronic and optical properties of the experimentally studied c-plane GaN/AlGaN quantum wells. This model confirmed
the existence of strong hole localization arising from the combined effects of the built-in polarization field along the growth
direction and the alloy fluctuations at the quantum well/barrier interface. However, for electrons these localization effects
are less pronounced in comparison to the holes. Furthermore, our calculations show that the attractive Coulomb interaction
between electron and hole results in exciton localization. This behavior is in contrast to the picture of independently localized
electrons and holes, often used to explain the radiative recombination process in c-plane InGaN/GaN quantum well systems.

• Journal Article Type: Article
• Acceptance Date: Oct 1, 2019
• Online Publication Date: Dec 11, 2019
• Publication Date: Dec 11, 2019
• Deposit Date: Nov 28, 2019
• Publicly Available Date: Jan 2, 2020
• Journal: Scientific Reports
• Print ISSN: 2045-2322
• Publisher: Nature Publishing Group
• Volume: 9
• Issue: 1
• Pages: 18862
• DOI: https://doi.org/10.1038/s41598-019-53693-2
• Publisher URL: https://doi.org/10.1038/s41598-019-53693-2
• Related Public URLs: https://www.nature.com/srep/
• Additional Information: Access Information : A Publisher Correction to this article can be found at https://doi.org/10.1038/s41598-020-62494-x (also in USIR: http://usir.salford.ac.uk/id/eprint/56790/); Funders : Royal Society International Exchange Grant;Engineering and Physical Sciences Research Council (EPSRC);Science Foundation Ireland; Grant Number: IE151046; Grant Number: EP/M010589/1; Grant Number: 13/SIRG/2210 and 12/RC/2276 P2