Optimization of the emission characteristics of light emitting diodes by surface plasmons and surface waveguide modes

Gianordoli, S.; Hainberger, Rainer; Köck, A.; Finger, N.; Gornik, E.; Hanke, C.; Korte, L.

doi:10.1063/1.1317538

Cited by 31 publications

(20 citation statements)

References 11 publications

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“…Gianordoli et al optimized the emission characterization of GaAs-based LED by SP. 25 Vuckovic et al reported the SP enhanced LED analyzing by both theoretically and experimentally. 26 Thus, great attention has been focused on SP enhanced emission.…”

Section: -9mentioning

confidence: 99%

Surface plasmon enhanced InGaN light emitter

et al. 2005

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We report a dramatic increase in the photoluminescence (PL) emitted from InGaN/GaN quantum wells (QW), obtained by covering these sample surface with thin metallic films. Remarkable enhancements of PL peak intensities were obtained from In 0.3 Ga 0.7 N QWs with 50 nm thick silver and aluminum coating with 10 nm GaN spacer. These PL enhancements can be attributed to strong interaction between QWs and surface plasmons (SPs). No such enhancements were obtained from samples coated with gold, as its well-known plasmon resonance occurs only at longer wavelengths. We also showed that QW-SP coupling increase the internal quantum efficiencies by measuring the temperature dependence of PL intensities. QW-SP coupling is a very promising method for developing the super bright light emitting diodes (LEDs). Moreover, we found that the metal nano-structure is very important facto to decide the light extraction. A possible mechanism of QW-SP coupling and emission enhancement has been developed, and high-speed and efficient light emission is predicted for optically as well as electrically pumped light emitters.

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Section: -9mentioning

confidence: 99%

Surface plasmon enhanced InGaN light emitter

et al. 2005

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“…3 Recently, we have reported a method for enhancing the light emission efficiency from InGaN QWs by controlling the energy transfer between QW emitters and surface plasmons ͑SPs͒. 4 The idea of SP enhanced light emission was previously described [5][6][7][8][9][10][11][12][13][14][15] and efficient SPenhanced visible light emission has been demonstrated. 4 Moreover, the enhancement of an emission rate is also very important for the development of communication technology and optical computing.…”

mentioning

confidence: 99%

Surface plasmon enhanced spontaneous emission rate of InGaN∕GaN quantum wells probed by time-resolved photoluminescence spectroscopy

Okamoto

Niki

Scherer

et al. 2005

Applied Physics Letters

359

248

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We observed a 32-fold increase in the spontaneous emission rate of InGaN/GaN quantum well ͑QW͒ at 440 nm by employing surface plasmons ͑SPs͒ probed by time-resolved photoluminescence spectroscopy. We explore this remarkable enhancement of the emission rates and intensities resulting from the efficient energy transfer from electron-hole pair recombination in the QW to electron vibrations of SPs at the metal-coated surface of the semiconductor heterostructure. This QW-SP coupling is expected to lead to a new class of super bright and high-speed light-emitting diodes ͑LEDs͒ that offer realistic alternatives to conventional fluorescent tubes. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.2010602͔Currently, InGaN-GaN quantum well ͑QW͒ based lightemitting diodes ͑LEDs͒ have been developed and expected to eventually replace more traditional fluorescent tubes as illumination sources. 1,2 However, the emission efficacy of commercial white LEDs is still substantially lower than that of fluorescent tubes. 3 Recently, we have reported a method for enhancing the light emission efficiency from InGaN QWs by controlling the energy transfer between QW emitters and surface plasmons ͑SPs͒. 4 The idea of SP enhanced light emission was previously described 5-15 and efficient SPenhanced visible light emission has been demonstrated. 4 Moreover, the enhancement of an emission rate is also very important for the development of communication technology and optical computing. However, spontaneous emission rates of InGaN-GaN QWs are usually reduced by the carrier localization effect 16,17 and the quantum confinement Stark effect, 18,19 and very difficult to enhance. There are only a few reports on the enhancement of the emission rates by reducing the piezo-electric field 20 and making photonic crystal structure. 21 We believe that our developed SP coupling technique has the potential to enhance the spontaneous emission rate dramatically. 4 Since the density of states of SP mode is much larger, the QW-SP coupling rate should be very fast, and this new path of a recombination can increase the spontaneous emission rate. However, clear evidence for fast rate of QW-SP coupling has not so far been reported on the SP enhanced emission. We investigate the direct observation of SP coupled spontaneous emission rate by using the timeresolved photoluminescence ͑PL͒ measurements here. Moreover, we consider the mechanisms and dynamics of energy transfer and light extraction. This study should also be very useful for further optimization of the QW-SP coupling condition and for designing even more efficient device structures.InGaN-GaN QW wafers were grown on 0001 oriented sapphire substrates by metal-organic chemical vapor deposition ͑MOCVD͒. The grown structures consist of a GaN ͑4 m͒ buffer layer, an InGaN SQW ͑3 nm͒ followed by a GaN cap layer ͑10 nm͒. A 50 nm thick silver layer was then evaporated on top of the wafer surface. To perform timeresolved PL measurements, the frequency doubled output from a mode-locked Ti: Al 2 O 3 laser was used to...

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“…Typically, when light emitted from multi-quantum wells of LED interacts with a metallic layer, a surface plasmon mode will be formed. This surface plasmon mode increases the density of states and spontaneous emission rate (Gianordoli et al, 2000;Hecker et al, 1999;Vuckovic et al, 2000), and thus helps to improve coupling from the multi-quantum wells (Neogi et al, 2002). There have been reports that successfully demonstrated enhancement in InGaN quantum well emission by means of enhancement of Purcell factor with surface plasmons making use of a metal film on top of an LED (Okamoto et al, 2004).…”

Section: Surface Plasmonmentioning

confidence: 99%