Experimental and theoretical study of thermally activated carrier transfer in InAs/GaAs multilayer quantum dots
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Experimental and theoretical study of thermally activated carrier transfer in InAs/GaAs multilayer quantum dots K. Abiedh1 · Z. Zaaboub1 · F. Hassen1 · T. David2 · L. Sfaxi1 · H. Maaref1 Received: 14 March 2020 / Accepted: 18 May 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In this paper, we have investigated the thermally activated carriers transfer mechanism in closely stacked InAs/GaAs quantum dots (QDs) by means of steady-state photoluminescence (PL) and time-resolved photoluminescence measurements. The 10 K PL spectrum exhibits double-emission peaks where the excitation power dependence reveals that these emission peaks are attributed to large and small QD groups. With increasing the sample temperature, an abnormal line-width shrinkage of large QDs (LQDs) is observed. The increase in PL decay lifetime of LQDs versus temperature is nicely explained as the electron and hole wave function overlap between dot layers induced by vertical electronic coupling effect. Using a thermal escape model, the activation energies for PL thermal quenching at high temperatures (above 80K) were derived from fitting the temperature-dependent PL decay lifetime data of LQDs and SQDs. The determined activation energies show that the escape of electron-hole pairs from QDs occurs via transfer channel located below the wetting layer. These results are well reproduced by a rate equation-based model treating the QDs as a localized-state ensemble. Our results emphasize the important role of the vertically stacked InAs/GaAs QDs structures with thin GaAs spacer layer to slow down the carrier PL decay lifetime of the thermal transfer process between QDs. This finding is important for the use of such structures as intermediate band in solar cells. Keywords Quantum dots · Bimodal size · Photoluminescence · Decay time · Localized carriers
1 Introduction Nanometer-scale semiconductor devices have been envisioned as next-generation technologies with high integration and functionality. QDs exhibit unique properties due to their quantum confinement in 3D. These unique properties have brought to light the great potential of quantum dots in optoelectronic applications. Particularly, self-assembled InAs/GaAs QDs have been broadly investigated for their outstanding optoelectronic properties such as high quantum yield, thermal stability and strong quantum confinement. Because of these properties, InAs/GaAs QDs have been utilized in many optoelectronics devices such as solar cells, * Z. Zaaboub [email protected] 1
Laboratoire de Micro‑Optoélectronique et Nanostructures, Faculté des Sciences de Monastir, Université de Monastir, Avenue de l’environnement, 5019 Monastir, Tunisia
Aix Marseille Université CNRS Université de Toulon IM2NP, UMR 7334, 13397 Marseille, France
2
lasers, light-emitting diodes and photodetectors [1–4]. Of special interest are arrays of vertically stacked self-assembled quantum dots (QDs) [5–8] since one expects enhancement in the performance of quantum dot lasers if many layers of nan
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