Effect of plasmonic losses on light emission enhancement in quantum-wells coupled to metallic gratings

Sadi, Toufik; Oksanen, Jani; Tulkki, Jukka

doi:10.1063/1.4845875

Cited by 17 publications

(16 citation statements)

References 29 publications

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“…More importantly, we demonstrated that the thickness of the GaN barrier separating the QW from the grating does not critically affect enhancement. This is in contrast to plasmonic structures relying on near-field effects, where enhancement strongly depends on this separation [7]; this is due to the fact that surface plasmon modes significantly lose their strength further away from the metal-semiconductor interface. Results reveal also that while the enhancement efficiency from the Ag-grated PVA structure can be maintained when the QW is located several hundreds of nanometers from the grating, the efficiency can vary strongly at the local level in a smaller spatial span in the order of tens of nanometers.…”

Section: Discussionmentioning

confidence: 70%

“…For the sake of keeping the discussion concise, we only describe the relationships used in the model. Full derivations of these relationships have been discussed elsewhere [7]. Equation (1) in multilayered geometries including a thin grated layer can be solved using the dyadic Green's function method of stratified media [15].…”

Section: Methodsmentioning

confidence: 99%

“…This results in a number of challenges related to very large leakage currents, depletion regions extending over the QW, current spreading and electrical contacting of the semiconductor surface. Even more importantly, SP-based extraction may introduce very large additional losses [7]. Another commonly used technique with a more modest enhancement relies on scattering caused by the roughness of the GaN surfaces [8], [9].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Improving Light Extraction From GaN Light-Emitting Diodes by Buried Nano-Gratings

Sadi

Oksanen

Tulkki

2014

IEEE J. Quantum Electron.

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Recent experimental work has demonstrated that the light extraction enhancement due to scattering by a metallic nano-grating in an InGaN/GaN quantum well (QW) structure can be improved significantly by burying the grating in a dielectric, such as polyvinyl alcohol (PVA). In this paper, we employ the fluctuational electrodynamics method to investigate the origin of this improvement and to provide guidelines on how to optimize emission efficiency in these structures. Our results show that metallic grating diffracts efficiently the high-intensity PVA resonances trapped in the structure, because of the large permittivity contrast between the metal and semiconductor, providing the reported exceptional enhancement for s-polarization. We also study the effect of two important physical factors in the enhancement: 1) the thickness of the GaN barrier separating the QW from the grating and 2) the thickness of the InGaN QW. Results reveal that the enhancement efficiency can be maintained even when the QW is not in the near field of the grating, for a QW-grating separation of up to 1 µm. This is in contrast to plasmonic structures, where enhancement strongly decreases as the separation is increased. However, the enhancement factor can also vary strongly at the local level in smaller spatial intervals. Results also show that the enhancement significantly decreases with the QW thickness due to the losses in the QW.Index Terms-GaN quantum well (QW) light-emitting structures, diffraction gratings, luminescence enhancement, fluctuational electrodynamics method.

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Section: Discussionmentioning

confidence: 70%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improving Light Extraction From GaN Light-Emitting Diodes by Buried Nano-Gratings

Sadi

Oksanen

Tulkki

2014

IEEE J. Quantum Electron.

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“…7,8 The SP modes are characterized by a high local density of states (LDOS), and as a consequence capture the main part of the emission, which can then be coupled to radiative light using the grating. 9,10 Recent experimental work has shown significant enhancement from GaN quantum-well (QW) light-emitting devices (LEDs) employing metallic gratings and other surface treatment. Indeed, enhancement factors as high as 15 have been reported in selected structures.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, enhancement factors as high as 15 have been reported in selected structures. In this work, we explore plasmonic enhancement and the associated losses in various structures, using first-principle theory based on fluctuational electrodynamics (FED) 9,11,12 and dyadic Green's functions (DGFs). 10,13,14 Specifically, we illustrate how the enhancement can be boosted by calculating the optimal structure parameters, such as the grating thickness, filling ratio and shape.…”

Section: Introductionmentioning

confidence: 99%

Optimized plasmonic light emission enhancement in III-N quantum-well emitters

2015

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In recent years, experimental work has shown that significant luminescence enhancement can be obtained from quantum-well (QW) light-emitting diodes (LEDs) by using metallic grating, which diffracts efficiently optical modes and resonances trapped in these structures and converts surface plasmon (SP) modes into radiative modes. We employ a powerful simulation tool to provide a deep insight into the physics of plasmonic enhancement and present guidelines on how to optimize light-extraction in III-nitride LED structures incorporating an emitting InGaN QW located in the vicinity of a grated silver surface. The model uses first-principle theory, coupling the dyadic Green's function formalism for solving Maxwell's equations to fluctuational electrodynamics, and employs a recursive and transparent solution method allowing the fields to be written in a closed form. We demonstrate the significant effect of the type of the periodic grating and layer structure on light-extraction efficiency by simulating various structures with different grating shapes and dimensions. Careful optimization of the grating features shows that the maximum enhancement can reach a factor of around 8 as compared to the flat semiconductor structure and that the plasmonic losses can be significantly reduced.

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ITO/nano‐Ag plasmonic window applied for efficiency improvement of near‐ultraviolet light emitting diodes

Tien

Zhang

Chung

et al. 2016

Physica Status Solidi (a)

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In this study, to enhance the emission efficiency of GaN‐based near‐ultraviolet light‐emitting diodes (NUV‐LEDs), the ITO/nano‐Ag plasmonic window which possessed localized surface plasmon (LSP) coupling effect was prepared on the roughened p‐GaN layer. The LSP coupling was generated on the grating nanostructure, resulting from the spin‐coated Ag nanoparticles onto the p‐GaN layer. To obtain an obvious LSP coupling, the Ag nanoparticles should be distributed on the p‐GaN uniformly. Thus, the p‐GaN layer was treated via the Ar‐plasma treatment, and it confirmed an uniform distribution of Ag nanoparticles can be prepared on the p‐GaN. The light output power (@350 mA) of the surface‐plasmon‐enhanced NUV‐LED (SPE‐NUV‐LED) with the Ar‐plasma treated p‐GaN possessed 73.7% improvement compared with that of the conventional NUV‐LED (C‐NUV‐LED). This improvement can be attributed to the formation of LSP effect in Ag nanoparticles embedded in the roughened p‐GaN, resulting from the coupling between the excitons in MQWs and the LSP in Ag nanoparticles.

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Effect of plasmonic losses on light emission enhancement in quantum-wells coupled to metallic gratings

Cited by 17 publications

References 29 publications

Improving Light Extraction From GaN Light-Emitting Diodes by Buried Nano-Gratings

Improving Light Extraction From GaN Light-Emitting Diodes by Buried Nano-Gratings

Optimized plasmonic light emission enhancement in III-N quantum-well emitters

ITO/nano‐Ag plasmonic window applied for efficiency improvement of near‐ultraviolet light emitting diodes

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