Excitation power dependence of photoluminescence spectra of GaSb type-II quantum dots in GaAs grown by droplet epitaxy

Kawazu, Takuya; Noda, Takeshi; Sakuma, Yoshiki; Sakaki, H.

doi:10.1063/1.4947464

Cited by 3 publications

(1 citation statement)

References 37 publications

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“…Figure 6(c) shows that the change in energy position is due to the thermalization effect by excess photo-carrier generation under high P ex at the band edge (λ = 550 nm). Secondly, the blue shift, other than the bandgap and broadening linewidth (Lorentz fitting), shows the intracentered transition of Ni +2 cluster interaction with LEMP or Ni +2 interaction with thermal activation of non-radiative centers, and defect-related non-radiative recombination dominates, as reported in type II heterostructures and perovskites [55][56][57][58]. InGaN/GaN quantum well (QW) exhibits a large energy blue shift of 150 meV due to localized states with density-of-states tails extending far into the bandgap [59,60].…”

Section: Resultsmentioning

confidence: 67%

Photon–carrier–spin coupling in a one-dimensional Ni(II)-doped ZnTe nanostructure

Bukhtiar,

Bao,

Khan

et al. 2024

Nanotechnology

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The transition metal ions doping in II-VI semiconductor can produce exciton magnetic polaron (EMP) and localized EMP, in which contain longitudinal optical (LO) phonon coupling will be discussed in this paper. Transition metal ion doping in II-VI semiconductor for dilute magnetic semiconductor (DMS) show emission by magnetic polarons together with hot carrier effect that need to be understand by its optical properties. The high excitation power responsible for hot carrier effect that suppressed the charge trapping effect for low exciton binding energy (8.12 meV) semiconductor even at room temperature. The large polaron radius exhibits strong interaction between carrier and magnetic polaron results anharmonicty effect in which side-band energy overtone to LO phonon. The photon-like polariton show the polarized spin interaction with LO that show strong spin-phonon polariton at room temperature. The temperature-dependent photoluminescence spectra of Ni-doped ZnTe show free exciton (FX), FX interact with 2LO phonon-spin interaction corresponding to 3T1(3F) → 1T1(1G) and EMP peaks with ferromagnetically coupled Ni ions at 3T1(3F) → 1E(1G). In addition, other d-d transition of single Ni ions (600-900 nm) appears at low energy side. Room temperature energy shift of 14-38 meV due to localized states with density of states tails extending far into bandgap related spin induced localization at valance band. These results show spin-spin magnetic coupling and spin-phonon interaction at room temperature that open a new horizon of optically controlled dilute magnetic semiconductor applications more realistic.

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Section: Resultsmentioning

confidence: 67%

Photon–carrier–spin coupling in a one-dimensional Ni(II)-doped ZnTe nanostructure

Bukhtiar,

Bao,

Khan

et al. 2024

Nanotechnology

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Structural differences between capped GaSb nanostructures grown by Stranski-Krastanov and droplet epitaxy growth modes

DeJarld

Yan

Luengo-Kovac

et al. 2017

Journal of Applied Physics

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Droplet epitaxy (DE) has emerged as an alternative to Stranski-Krastanov (SK) as a method for epitaxial nanostructure formation. We find significant structural differences of similar sized nanostructures embedded in GaAs between the two methods. Atomic force microscopy and atom probe tomography measurements reveal that uncapped and capped SK structures resemble each other. However, the DE nanostructures appear as rings topographically but are quantum dots compositionally. A GaSb wetting layer is present regardless of the growth method and shares a nearly identical Sb concentration profile. DE nanostructures are shown to have a lower Sb concentration, and transmission electron microscopy measurements reveal that they produce less strain on the capping layer. Despite significant structural differences, SK and DE nanostructures exhibit the same photoluminescence response, suggesting that the emission is from a shared feature such as the wetting layer, rather than the nanostructures.

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Reducing the Photodegradation of Perovskite Quantum Dots to Enhance Photocatalysis in CO2 Reduction

2021

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Solution-processed perovskite quantum dots (QDs) have been intensively researched as next-generation photocatalysts owing to their outstanding optical properties. Even though the intrinsic physical properties of perovskite QDs have been significantly improved, the chemical stability of these materials remains questionable. Their low long-term chemical stability limits their commercial applicability in photocatalysis. In this study, we investigated the photodegradation mechanisms of perovskite QDs and their hybrids via photoluminescence (PL) by varying the excitation power and the ultraviolet (UV) exposure power. Defects in perovskite QDs and the interface between the perovskite QD and the co-catalyst influence the photo-stability of perovskite QDs. Consequently, we designed a stable perovskite QD film via an in-situ cross-linking reaction with amine-based silane materials. The surface ligand comprising 2,6-bis(N-pyrazolyl)pyridine nickel(II) bromide (Ni(ppy)) and 5-hexynoic acid improved the interface between the Ni co-catalyst and the perovskite QD. Then, ultrathin SiO2 was fabricated using 3-aminopropyltriethoxy silane (APTES) to harness the strong surface binding energy of the amine functional group of APTES with the perovskite QDs. The Ni co-catalyst content was further increased through Ni doping during purification using a short surface ligand (3-butynoic acid). As a result, stable perovskite QDs with rapid charge separation were successfully fabricated. Time-correlated single photon counting (TCSPC) PL study demonstrated that the modified perovskite QD film exhibited slow photodegradation owing to defect passivation and the enhanced interface between the Ni co-catalyst and the perovskite QD. This interface impeded the generation of hot carriers, which are a critical factor in photodegradation. Finally, a stable red perovskite QD was synthesized by applying the same strategy and the mixture between red and green QD/Ni(ppy)/SiO2 displayed an CO2 reduction capacity for CO (0.56 µmol/(g∙h)).

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Excitation power dependence of photoluminescence spectra of GaSb type-II quantum dots in GaAs grown by droplet epitaxy

Cited by 3 publications

References 37 publications

Photon–carrier–spin coupling in a one-dimensional Ni(II)-doped ZnTe nanostructure

Photon–carrier–spin coupling in a one-dimensional Ni(II)-doped ZnTe nanostructure

Structural differences between capped GaSb nanostructures grown by Stranski-Krastanov and droplet epitaxy growth modes

Reducing the Photodegradation of Perovskite Quantum Dots to Enhance Photocatalysis in CO2 Reduction

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