Free charges<i>versus</i>excitons: photoluminescence investigation of InGaN/GaN multiple quantum well nanorods and their planar counterparts

Chen, Weijian; Wen, Xiaoming; Yang, Jianfeng; Latzel, Michael; Patterson, Robert; Huang, Shujuan; Shrestha, Santosh; Jia, Baohua; Moss, David J.; Christiansen, Silke; Conibeer, Gavin

doi:10.1039/c7nr07567g

Cited by 19 publications

(19 citation statements)

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“…This means that here the carrier densities are low enough, so that exciton radiative emission rate does not grow exponentially with density, as it is usually observed in polar heterostructures. 16,17,[25][26][27][28] In conclusion, we have shown that dipolar excitons can be efficiently trapped in the plane of GaN/(AlGa)N QWs. In previous works on GaN QWs hosting dipolar excitons, the mutual repulsion of excitons led to a fast radial expansion and dilution of the exciton gas, accompanied by dramatic variation of the exciton energy and lifetime.…”

Section: (C))mentioning

confidence: 68%

“…12,13 While excitons in GaN-based nanostructures have relatively high binding energies and small Bohr radii 21 (as compared to GaAs-based structures) and thus could exhibit quantum properties at higher temperatures, 22 the additional challenges that must be faced to achieve such degree of control are numerous. These may include nonradiative losses, 23 megavolt per centimeter-strong built-in electric fields, 24 an exponential dependence of the lifetime on the exciton density under high excitation conditions, [25][26][27] and the guided-and-scattered light that must be distinguished from the exciton photoluminescence (PL). 17,28 In this letter we overcome those challenges and report on the realization of ∼ 10 µm ×50 µm-size thermalized exciton fluid, trapped in the plane of a GaN/(GaAl)N quantum well grown on a free-standing GaN substrate.…”

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confidence: 99%

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Trapping Dipolar Exciton Fluids in GaN/(AlGa)N Nanostructures

et al. 2019

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Dipolar excitons offer a rich playground for both design of novel optoelectronic devices and fundamental many-body physics. Wide GaN/(AlGa)N quantum wells host a new and promising realization of dipolar excitons. We demonstrate the inplane confinement and cooling of these excitons, when trapped in the electrostatic potential created by semitransparent electrodes of various shapes deposited on the sample surface. This result is a prerequisite for the electrical control of the exciton densities and fluxes, as well for studies of the complex phase diagram of these dipolar bosons at low temperature. Keywords exciton fluid, electrostatic traps, cooling, gallium nitride Dipolar excitons, Coulomb-bound but spatially separated electron-hole pairs, have a long life-time and a built-in dipole moment that offer an opportunity for the cooling and electrical 1 arXiv:1902.02974v1 [physics.app-ph] 8 Feb 2019 control of exciton fluids. 1-7 Various intriguing quantum phenomena including Bose-Einsteinlike condensation, darkening and superfluidity of excitons have been recently reported. 8-15Albeit demonstrated at very low temperatures, those phenomena are promising for better understanding of new states of matter, but also for potential applications in excitonic devices with novel functionalities. 7The recent emergence of high quality wide-bandgap semiconductor quantum wells (QWs) and two-dimensional Van der Waals heterostructures, hosting dipolar excitons with large exciton binding energies and built-in electric fields, has given a new impetus to this research. [16][17][18][19][20] Room temperature exciton transport in GaN/(AlGa)N QWs has been demonstrated, 17 as well as its electrical control in MoS 2 −WSe 2 heterostructures. 20 The latter is

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confidence: 68%

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confidence: 99%

Trapping Dipolar Exciton Fluids in GaN/(AlGa)N Nanostructures

et al. 2019

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“…Figure a is the steady‐state PL spectra of the MAPbBr x I 3‐ x microplatelets before and after probing laser scanning (488 nm at 200 mW cm −2 ) via a confocal laser scanning microscope. The light path of the microscope is shown in Figure S1 in the Supporting Information, and other laser set‐up details are also provided in the Experimental Section in the Supporting Information. The pristine PL of microplatelets peaks at 550 nm.…”

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confidence: 99%

Tracking Dynamic Phase Segregation in Mixed‐Halide Perovskite Single Crystals under Two‐Photon Scanning Laser Illumination

et al. 2019

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Photoinduced phase segregation in mixed halide perovskites has received considerable attention due to its critical roles in diminishing device performance in photovoltaic and light‐emitting applications. Here, dynamic photoinduced phase segregation and dark recovery in mixed halide perovskite single crystal microplatelets are investigated, combining depth‐resolved, temporal‐resolved, and detection‐wavelength selective spectroscopic imaging techniques. Under identical illumination, the edges and interior of microplatelets exhibit significantly different phase segregation. An intimate correlation of PL dynamics between I‐phase and Br‐phase indicates that the halide substitution is the dominant effect. In the dark, the phase‐segregated crystals reversibly recover to the stable equivalence. This work clarifies the critical role of the edge state of the microplatelets and reveals the physical mechanism of phase segregation in mixed halide perovskites, which is of crucial importance for their applications in photovoltaics and photonics.

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“…Furthermore, the special properties of nanostructures that carriers and photons are confined in the transverse directions and propagate freely in longitudinal direction [20][21] can produce special optical phenomena. In addition, some reports [22][23] on 3D PL imaging on the In 0.18 Ga 0.82 N/GaN MQW NRs are helpful for understanding the optical properties. In order to study the optical phenomena of nanorods, a confocal laser scanning microscope (CLSM) can be used to perform 3D scanning to understand the interaction between light and nanostructures.…”

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confidence: 99%

3D fluorescence confocal microscopy of InGaN/GaN multiple quantum well nanorods from a light absorption perspective

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Yang

et al. 2021

Nanoscale Adv.

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Free chargesversusexcitons: photoluminescence investigation of InGaN/GaN multiple quantum well nanorods and their planar counterparts

Abstract: Photoexcited carriers are mainly excitons in InGaN/GaN multiple quantum well planar layers while free electron holes are greatly increased in nanorods.

Cited by 19 publications

References 54 publications

Trapping Dipolar Exciton Fluids in GaN/(AlGa)N Nanostructures

Trapping Dipolar Exciton Fluids in GaN/(AlGa)N Nanostructures

Tracking Dynamic Phase Segregation in Mixed‐Halide Perovskite Single Crystals under Two‐Photon Scanning Laser Illumination

3D fluorescence confocal microscopy of InGaN/GaN multiple quantum well nanorods from a light absorption perspective

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