Recycling of guided mode light emission in planar microcavity light emitting diodes

Neve, H. De; Blondelle, J.; Daele, Peter Van; Demeester, Piet; Baets, Roel; Borghs, Gustaaf

doi:10.1063/1.118226

Cited by 133 publications

(62 citation statements)

References 7 publications

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“…This is also why in the work De Neve et al [86], the best external e$ciency was obtained for large area devices. make current injection much more di$cult and either lateral injection is required [58] or the use of conducting dielectrics, such as Indium Tin Oxide (ITO).…”

Section: Thin Cavitiesmentioning

confidence: 76%

“…The extraction e$ciency then increases because if, out of the k modes that the emission process can "ll, a single mode is extracted, the extraction e$ciency (and hence the external e$ciency) scales as 1/k. This is, in naive terms, the main factor behind the 23% external quantum e$ciency already obtained with MCLEDs [85,86]. The other factor involved is photon recycling, which will be discussed below.…”

Section: Thin Cavitiesmentioning

confidence: 99%

“…Microcavity LEDs (MCLEDs) are the "rst manifestation of this concept. They cannot genuinely be referred to as photonic crystals, but share the concept of using periodic structures for strong con"nement: 23% external e$ciency, extracted from a single facet, has already been demonstrated [85,86]. Extending this concept into two and three dimensions should push the limit further and lead to devices with an external e$ciency up to 50% or even beyond.…”

Section: Light Emitting Diodes (Leds)mentioning

confidence: 99%

“…Photons, particularly those emitted into the waveguide modes, can have a high probability of reabsorption if the interaction length with the active layer is long enough [86] and the overlap with the active layer is su$ciently strong [88]. An impressive demonstration of the extent to which the recycling e!ect can be used was given by Schnitzer and Yablonovitch [83], where each photon was re-emitted for an average 25 times, leading to a total external e$ciency of 72%.…”

Section: Photon Recyclingmentioning

confidence: 99%

“…The realisation of a thin (e.g. one wavelength thick) cavity device involves a -thick central layer bounded by a metal mirror on one side and by a GaAs/AlGaAs Bragg stack on the other [86], forming a structure that supports between 4 and 5 modes. Although the cavity spacer is only 1 wavelength thick, which suggests that the cavity can support two modes, the "eld penetrates substantially into the mirrors and thus increases the e!ective cavity length.…”

Section: Thin Cavitiesmentioning

confidence: 99%

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Photonic crystals in the optical regime â past, present and future

Krauss

Rue

1999

Progress in Quantum Electronics

445

141

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During the last decade, photonic crystals, also known as photonic microstructures or photonic bandgap structures, have matured from an intellectual curiosity concerning electromagnetic waves to a "eld with real applications in both the microwave and optical regime. In this review, we shall focus on progress and the prospects for semiconductor structures that mainly involve guided modes interacting with periodic structures, but we also evaluate alternative material systems and fabrication methods, e.g. those based on self-organisation. We shall go from basic concepts, via a discussion of the state of the art, to device applications. Naturally, the discussion of the applications will be more speculative, but we attempt to evaluate the real prospects o!ered by photonic crystals at optical frequencies while considering practical limitations. In doing so, we identify a variety of areas such as the combination of quantum dot light emitters with photonic crystals that seem particularly promising. We discuss the prospects for enhanced light}matter interactions in photonic crystals and the related material and design issues. Overall, the aim of this review is to introduce the reader to the concepts of photonic crystals, describe the state of the art and attempt to answer the question of what uses these peculiar structures may have.

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Section: Thin Cavitiesmentioning

confidence: 76%

Section: Thin Cavitiesmentioning

confidence: 99%

Section: Light Emitting Diodes (Leds)mentioning

confidence: 99%

Section: Photon Recyclingmentioning

confidence: 99%

Section: Thin Cavitiesmentioning

confidence: 99%

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Photonic crystals in the optical regime â past, present and future

Krauss

Rue

1999

Progress in Quantum Electronics

445

141

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Modelling of Extraction Efficiency of GaN-Based Resonant Cavity Light Emitting Diodes Emitting at 510 nm

Shaw

McCormack

Bradley

et al. 2002

phys. stat. sol. (a)

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PACS: 81.05.Ea; 85.60.BtThe design of GaN resonant cavity light emitting diodes (RCLEDs) emitting at 510 nm is optimised for maximum extraction efficiency into numerical apertures (NAs) of 1.0 and 0.5. The optimisation is performed as a function of the Al fraction in the AlGaN/GaN distributed Bragg reflector (DBR) cavity mirror and of the InGaN/GaN quantum well (QW) emission linewidth. The calculated enhancement factors of the extraction efficiency compared to a bulk LED for emission into a NA of 1.0 (0.5) increase from 3.0 (3.4) for a single metal mirror LED structure to 4.2 (5.8) for a metal-AlN/GaN DBR RCLED structure. The dependence of efficiency and optimum number of DBR pairs on Al fraction in the DBR, QW emission linewidth, and emission NA is discussed in terms of cavity modal properties.Introduction Determining the optimum design and performance of GaN resonant cavity light emitting diodes (RCLEDs) is essential for assessing the potential and limitations of these devices in practical applications. In particular, the impact of the relatively small refractive index variation of AlGaN with Al fraction compared to AlGaAs on the properties of AlGaN/GaN distributed Bragg reflectors (DBRs) has important implications for GaN RCLEDs incorporating these mirrors.In RCLEDs the coupling of emission from the active layer to the modes of the cavity produces a modification of the spatial and spectral properties of the spontaneous emission process. This modification of the spontaneous emission process can be used to improve the extraction efficiency compared to convention light emitting diodes (LEDs) by increasing emission at internal angles less than the critical angle for light to escape from the device, as first demonstrated by De Neve et al. [1]. The capacity of a generic planar cavity structure to enhance the light extraction efficiency through a single surface is extensively discussed in two seminal papers by Benisty et al. [2,3]. One promising application of RCLEDs is as sources for plastic optical fibre (POF)-based local area networks, where red RCLEDs whose emission wavelength is matched to the POF transmission window at 650 nm have demonstrated impressive performance [4]. Additional POF transmission windows exist at 510 and 570 nm. These wavelengths are accessible using III-V nitride semiconductors, whose emission properties are less temperature dependent than the AlGaInP materials used for emission in the red. These materials potentially offer a reduced temperature sensitivity of device performance, as is required for POF applications in automotive and avionic environments. In this paper, the optimum design of a GaN RCLED emitting at 510 nm for maximum extraction efficiency into air and into a typical POF numerical aperture (NA) of 0.5 is discussed.

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