InxGa1–xN/AlyGa1–yN violet light emitting diodes with reflective p-contacts for high single sided light extraction

Mensz, P. M.; Kellawon, P.; Roijen, R. van; Kozodoy, P.; DenBaars, Steven P.

doi:10.1049/el:19971379

Cited by 12 publications

(7 citation statements)

References 5 publications

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“…Thus improvement of light extraction efficiency has been a focus of research [20] and several methods such as metal reflection layer [21], omni-directional reflector [22], a textured surface [23][24][25][26], and a flip-chip packaging method [27] have been proposed to enhance the light extraction of the highly efficient LEDs. Photonic crystal (PC) structures have also been investigated as an effort of improving the extraction efficiency in LEDs [3][4][5][6][7].…”

Section: Photonic Crystal Ledmentioning

confidence: 99%

Application of nanoimprint lithography to nano-optics: wire grid polarizer and photonic crystal LED

et al. 2007

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Two optical devices with nano-scale subwavelength structures have been fabricated by using nanoimprint lithography (NIL). (1) Wire grid polarizer (WGP) is one of key optical components for projection displays with liquid crystal microdisplay. Although WGP with 140 nm pitch is commercially available now, it still poses a problem with low extinction ratio (ER) for blue color. Since the ER can be increased by reducing the pitch, fabrication of a WGP with 100 nm pitch was attempted by NIL. We successfully developed thermal nanoimprint and aluminum dry etching processes. Fabricated WGPs showed twice higher ER than 140 nm pitch one. (2) Photonic crystal (PC) structures on LED have been known to enhance the light extraction significantly. Although e-beam lithography has been used for the proof of principle, it is far from real production method. We applied thermal NIL to fabricate PC structures in p-GaN layer of green LED. To identify the PC effect, two structures were fabricated and compared. One structure makes the green light of 525 nm wavelength fall within the photonic band gap (PBG) while the other puts it outside of PBG. The former structure showed 9-fold increment of photoluminescence compared to LED without PC structures, while the latter showed only 6-fold increment.

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Section: Photonic Crystal Ledmentioning

confidence: 99%

Application of nanoimprint lithography to nano-optics: wire grid polarizer and photonic crystal LED

et al. 2007

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“…To increase the light extraction efficiency of LEDs, several approaches such as the use of omnidirectional reflectors, metal reflection layers, photonic crystals, flip-chip packaging, and textured surfaces have been reported. [8][9][10][11][12][13][14] In these cases, each technique has its own processing and economic drawbacks when applied to large-scale production such as the difficulty in growing an omnidirectional reflector, the complicated processing, and difficulty in controlling the processing of fabricating the textured surfaces. Alternatively, groups have presented GaN-based LEDs using a coating of transparent balls with a high refractive index on n-GaN surfaces 15) and SiO 2 /polystyrene microlens arrays on p-GaN surface.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Light Extraction from GaN-Based Light-Emitting Diodes by Coating Surface with Al₂O₃ Powder

Kim

Yang

et al. 2009

jjap

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GaN-based light-emitting diodes (LEDs) were fabricated by coating Al 2 O 3 powder on a p-GaN and a semitransparent p-contact metal surface to increase the extraction probability of the internal reflected photons through the Al 2 O 3 powder. The density of the $300-nmdiameter Al 2 O 3 powder was about 1:9 Â 10 13 cm À2 on both surfaces. The forward voltages of the LEDs coated with Al 2 O 3 powder on the p-GaN surface and the semitransparent p-contact metal surface were 4.15 and 3.42 V at 20 mA, respectively. The light output powers of both LED structures with Al 2 O 3 powder coated on the p-GaN and semitransparent p-contact metal surfaces were increased by almost 30% compared with the conventional LED structure without Al 2 O 3 powder coating. #

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“…Consequently, elimination of the semitransparent contact should result in improvement of light extraction. For nitride LEDs emitting in the wavelengths from 460 nm to 530 nm, it has been shown by Wierer et al [1] that the extraction efficiency is increased by ~ 60 % by packaging the LED in a flip chip configuration. The additional advantage of the flip chip geometry is the reduced thermal resistance since the p-n junction is much closer to the heat sink.…”

Section: Introductionmentioning

confidence: 99%

Ultraviolet nitride LED fabrication for high-flux white LED

Venugopalan¹,

DiCarlo²,

Gao³

et al. 2003

SPIE Proceedings

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The requirements for maximizing the external quantum efficiency of UV nitride LEDs are discussed. It is shown that as the chip wavelength progressively decreases, nitride epi growth on a sapphire substrate becomes advantageous in terms of light extraction. The epilayer requirements for UV LEDs dictate the growth of n-AlGaN, with increasing Al contents, and the growth of UV-transparent p-GaN. It is shown that MOCVD growth in a Emcore D-180 or Ganzilla reactor is ideal for meeting the stringent epilayer requirements. Increasing light extraction efficiency and wall-plug efficiency also requires optimization of the reflecting P-contact. The relative merits of Al-and Ag-based reflecting contacts are discussed. Performance data for UV LEDs on sapphire, for drive currents up to 700 mA is shown. Finally, a practical high power UV-based white lamp is demonstrated.

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InxGa1–xN/AlyGa1–yN violet light emitting diodes with reflective p-contacts for high single sided light extraction

Cited by 12 publications

References 5 publications

Application of nanoimprint lithography to nano-optics: wire grid polarizer and photonic crystal LED

Application of nanoimprint lithography to nano-optics: wire grid polarizer and photonic crystal LED

Enhancement of Light Extraction from GaN-Based Light-Emitting Diodes by Coating Surface with Al₂O₃ Powder

Ultraviolet nitride LED fabrication for high-flux white LED

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InxGa1–xN/AlyGa1–yN violet light emitting diodes with reflective p-contacts for high single sided light extraction

Cited by 12 publications

References 5 publications

Application of nanoimprint lithography to nano-optics: wire grid polarizer and photonic crystal LED

Application of nanoimprint lithography to nano-optics: wire grid polarizer and photonic crystal LED

Enhancement of Light Extraction from GaN-Based Light-Emitting Diodes by Coating Surface with Al2O3 Powder

Ultraviolet nitride LED fabrication for high-flux white LED

Contact Info

Product

Resources

About

Enhancement of Light Extraction from GaN-Based Light-Emitting Diodes by Coating Surface with Al₂O₃ Powder