Carrier Dynamics in UV InGaN Multiple Quantum Well Inverted Hexagonal Pits

Llopis, Antonio; Lin, Jie; Li, Jianyou; Pereira, S.; Neogi, Arup

doi:10.1109/jstqe.2009.2019616

Cited by 5 publications

(4 citation statements)

References 12 publications

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“…Although a correlation between nanometer‐scale strain relaxation and band‐gap energies of individual localized emission centers cannot be excluded, it is rather unlikely that shifts in transition energies larger than ≈300 meV are caused by inhomogeneous strain relaxation in In 0.22 Ga 0.78 N multiple QW structures 17, 36. It should be mentioned that structural imperfections, such as V‐shaped pits, can also lead to the formation of localized luminescent centers 37, 38. However, these highly effective radiative recombination sites have been shown to emit at energies a few hundred meV higher than those of the QWs 37, 39.…”

Section: Discussionmentioning

confidence: 99%

Two Distinct Origins of Highly Localized Luminescent Centers within InGaN/GaN Quantum‐Well Light‐Emitting Diodes

Dey

Layek

Raja

et al. 2011

Adv Funct Materials

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The high light‐output efficiencies of InxGa1‐xN quantum‐well (QW)‐based light‐emitting diodes (LEDs) even in presence of a large number of nonradiative recombination centers (such as dislocations) has been explained by localization of carriers in radiative potential traps, the origins of which still remain unclear. To provide insights on the highly efficient radiative traps, spectrally resolved photoluminescence (PL) microscopy has been performed on green‐light‐emitting In0.22Ga0.78N QW LEDs, by selectively generating carriers in the alloy layers. PL imaging shows the presence of numerous inhomogeneously distributed low‐band‐gap traps with diverse radiative intensities. PL spectroscopy of a statistically relevant number of individual traps reveals a clear bimodal distribution in terms of both band‐gap energies and radiative recombination efficiencies, indicating the presence of two distinct classes of carrier localization centers within the same QW sample. Disparity in their relative surface coverage and photoemission “blinking” characteristics suggests that the deep traps originate from local compositional fluctuations of indium within the alloy, while the shallow traps arise from nanometer‐scale thickness variations of the active layers. This is further supported by Poisson–Schrödinger self‐consistent calculations and implies that radiative traps formed due to both local indium content and interface‐morphology‐related heterogeneities can coexist within the same QW sample.

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Section: Discussionmentioning

confidence: 99%

Two Distinct Origins of Highly Localized Luminescent Centers within InGaN/GaN Quantum‐Well Light‐Emitting Diodes

Dey

Layek

Raja

et al. 2011

Adv Funct Materials

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“…The first step is the absorption of excitation photon at $3.40 eV by the quantum well, followed by an enhancement of the light emission from the MQWs via coupling to the resonant LSP modes that subsequently couples to far-field radiation and emits the photons. 16 However, a fraction of the light generated within the MQWs is absorbed and a part of the generated photons are scattered by the metal nanoparticles with plasmon frequency resonant to the emission energy of the quantum well. In case of Au NPs, as the LSP energy is detuned from the emission energy of the MQW, the reabsorption or scattering by the NP does not affect the emission process.…”

Section: -mentioning

confidence: 99%

“…This significant difference for Au filled IHP MQWs is due to the potential barriers caused by narrowed QWs. The narrowing in IHPs results in graded index potential well 16 due to which the threading dislocation act as a sink for carriers. It hinders the carrier concentration from increasing significantly within the IHP QWs.…”

mentioning

confidence: 99%

Comparison of electrostatic and localized plasmon induced light enhancement in hybrid InGaN/GaN quantum wells

Lin

Llopis

Krokhin

et al. 2014

Applied Physics Letters

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The light enhancement phenomena in InGaN/GaN multi-quantum wells (MQWs) infiltrated with metal nanoparticles (NPs) are studied using resonant and off-resonant localized plasmon interactions. The emission and recombination characteristics of carriers in InGaN/GaN MQW structures with inverted hexagonal pits (IHPs) are modified distinctly depending on the nature of their interaction with the metal NPs and with the pumping and emitted photons. It is observed that the emission intensity of light is significantly enhanced when the emission energy is off-resonant to the localized plasmon frequency of the metal nanoparticles. This results in enhanced emission from MQW due to Au nanoparticles and from IHPs due to Ag nanoparticles. At resonant-plasmon frequency of the Ag NPs, the emission from MQWs is quenched due to the re-absorption of the emitted photons, or due to the drift carriers from c-plane MQWs towards the NPs because of the Coulomb forces induced by the image charge effect

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“…The measured spectra were then fitted using multiple Gaussians to extract the intensities of the PR using the model described in Ref. 13. Due to specular reflection of the excitation source, the fitting was not possible at 55 and 60 and hence the fitting results for those angles were discarded.…”

Section: -mentioning

confidence: 99%

Plasmonic modification of electron-longitudinal-optical phonon coupling in Ag-nanoparticle embedded InGaN/GaN quantum wells

Llopis

Pereira

Watson

et al. 2014

Applied Physics Letters

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Surface plasmon enhanced GaN and InGaN quantum wells (QWs) show promise for use as room-temperature light emitters. The effectiveness of the plasmon enhancement, however, is limited by the strong electron/hole and longitudinal optical phonon coupling found in the III-V nitrides. The electron-phonon coupling within semiconductor QWs has been modified using silver nanoparticles embedded within the QWs. Direct evidence is provided for this change via confocal Raman spectroscopy of the samples. This evidence is augmented by Angle-dependent photoluminescence experiments which show the alteration of the electron-phonon coupling strength through measurement of the emitted phonon replicas. Together these demonstrate a direct modification of carrier-phonon interactions within the system, opening up the possibility of controlling the coupling strength to produce high-efficiency room-temperature light emitters.

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Carrier Dynamics in UV InGaN Multiple Quantum Well Inverted Hexagonal Pits

Cited by 5 publications

References 12 publications

Two Distinct Origins of Highly Localized Luminescent Centers within InGaN/GaN Quantum‐Well Light‐Emitting Diodes

Two Distinct Origins of Highly Localized Luminescent Centers within InGaN/GaN Quantum‐Well Light‐Emitting Diodes

Comparison of electrostatic and localized plasmon induced light enhancement in hybrid InGaN/GaN quantum wells

Plasmonic modification of electron-longitudinal-optical phonon coupling in Ag-nanoparticle embedded InGaN/GaN quantum wells

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