GaN micro-light-emitting diode arrays with monolithically integrated sapphire microlenses

Choi, H. W.; Liu, C.; Gu, Erdan; McConnell, Gail; Girkin, John M.; Watson, I. M.; Dawson, Martin D.

doi:10.1063/1.1690876

Cited by 122 publications

(67 citation statements)

References 10 publications

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“…Positive microlens arrays in GaN and GaN-based devices have been reported recently in detail by Oder et al 4 and Choi et al 5 respectively, where the importance of being able to form micro-optical elements 6 from this technologically significant material was highlighted. Here we show that negative and bifocal lenses can also be fabricated from epitaxial GaN.…”

Section: Methodsmentioning

confidence: 94%

Fabrication and evaluation of GaN negative and bifocal microlenses

Choi

Liu

et al. 2005

Journal of Applied Physics

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Methods of fabricating negative and bifocal microlens arrays have been demonstrated in this paper. The technique of photoresist molding using a sapphire positive lens template was used for the patterning of negative microlenses, while the bifocal microlens arrays were fabricated using a two-step etch process. In both cases, the lenses were etched using inductively coupled plasma. Microlenses with diameters as small as 10 µm have been demonstrated and were characterized using atomic force microscopy and confocal microscopy. The lens arrays were found to be smooth, uniform, and to have focal lengths consistent with their design and calculated values

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Section: Methodsmentioning

confidence: 94%

Fabrication and evaluation of GaN negative and bifocal microlenses

Choi

Liu

et al. 2005

Journal of Applied Physics

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“…The light extraction efficiency is a key factor of the external quantum efficiency of LEDs. There have been several reports to improve the light extraction efficiency, for example, a cone-shaped surface texture via laser lift-off [3], a microlens array and photonic crystal structure which are subjected sophisticated process techniques [4,5]. Above those, however, make device fabrication further complicated.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and optical properties of blue LEDs with silica microsphere coating

Kusakabe¹,

Funazaki²,

Okamoto³

et al. 2007

Phys. Status Solidi (c)

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We report the enhancement of light extraction efficiency of InGaN-based blue light emitting diodes by using a surface light-scattering layer. A number of SiO 2 microspheres embedded into a ZrO 2 thin layer played a role of a light-scattering medium. Coating the light-scattering layer on device surface, the interference fringes of electroluminescence (EL) spectra were eliminated and the EL intensity around 440 -450 nm was increased by a factor of 1.3.

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“…The superior mechanical characteristics, such as high hardness and high-temperature stability, enable the sapphire to be used as a substrate for LED devices because it can endure the severe temperature conditions of GaN film deposition [1][2][3]. Furthermore, it is widely used in other fields, such as laser diodes and laser sources for storage and optical media [4][5][6][7][8][9], due to its combination of high chemical resistance and mechanical characteristics as well as its transparency [10][11][12].…”

Section: Introductionmentioning

confidence: 99%