High Brightness GaN-Based Light-Emitting Diodes

Lee, Ya Ju; Lu, Tien−Chang; Kuo, Hao‐Chung; Wang, Shing-Chung

doi:10.1109/jdt.2007.894380

Cited by 46 publications

(19 citation statements)

References 21 publications

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“…8,9 On the other hand, the guided-light scattering efficiency of LEDs prepared on PSS is much stronger than those prepared on a flat sapphire substrate. 10 As a result, stronger LED output intensity due to the random scattering of propagating light 11 can also be achieved. Moreover, high light extraction efficiency LEDs with embedded air voids on a patterned substrate 12 or with embedded two-floor air prism array 13 have also been reported.…”

Section: Institute Of Electro-optical Science and Engineering Centermentioning

confidence: 99%

GaN-based light emitting diodes with embedded SiO2 pillars and air gap array structures

Lai

Yang

et al. 2010

Applied Physics Letters

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We demonstrated GaN-based light emitting diodes (LEDs) with different embedded heights of SiO2 pillars and air gap array structures. The air gap on top of the SiO2 pillars were also realized using the enhanced epitaxial lateral overgrowth mode. With the embedded SiO2 pillars and air gap array structures, we achieved a smaller reverse leakage current due to the lateral growth-induced crystal quality improvement. Moreover, under 20 mA current injections, the output powers were 3.04, 4.23, 4.66, and 4.44 mW for conventional LED, LEDs with embedded 200 and 500 nm height of SiO2 pillars and air gaps, 500 nm height of SiO2 pillars and air gaps, and 700 and 400 nm height of SiO2 pillars and air gaps, respectively. We found that the embedded 500 nm height SiO2 pillars and 500 nm height air gap array structures could enhance LED output power by more than 50% due to the enhanced guided-light scattering efficiency in our study.

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Section: Institute Of Electro-optical Science and Engineering Centermentioning

confidence: 99%

GaN-based light emitting diodes with embedded SiO2 pillars and air gap array structures

Lai

Yang

et al. 2010

Applied Physics Letters

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“…The average radius of phosphor particles is 5-8 μm. In one LED module, the number of phosphor particles is generally more than 1Â10 5 per mm 3 . This indicates that there may be millions of phosphor particles in a phosphor layer.…”

Section: Phosphor Coatingmentioning

confidence: 99%

“…Since the first light-emitting diode (LED) was invented by Holonyak and Bevacqua in 1962 [1], LEDs have made remarkable progress over the past four decades with the rapid development of epitaxy growth [2], chip design and manufacture [3], packaging structure, processes and materials. In the early 1990s, Nakamura successfully grew blue and green LEDs on a GaN substrate [4,5].…”

Section: Introductionmentioning

confidence: 99%

Status and prospects for phosphor-based white LED packaging

Liu

Wang

et al. 2009

Front. Optoelectron. China

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The status and prospects for high-power, phosphor-based white light-emitting diode (LED) packaging have been presented. A system view for packaging design is proposed to address packaging issues. Four aspects of packaging are reviewed: optical control, thermal management, reliability and cost. Phosphor materials play the most important role in light extraction and color control. The conformal coating method improves the spatial color distribution (SCD) of LEDs. High refractive index (RI) encapsulants with high transmittance and modified surface morphology can enhance light extraction. Multi-phosphor-based packaging can realize the control of correlated color temperature (CCT) with high color rendering index (CRI). Effective thermal management can dissipate heat rapidly and reduce thermal stress caused by the mismatch of the coefficient of thermal expansion (CTE). Chip-on-board (CoB) technology with a multilayer ceramic substrate is the most promising method for high-power LED packaging. Low junction temperature will improve the reliability and provide longer life. Advanced processes, precise fabrication and careful operation are essential for high reliability LEDs. Cost is one of the biggest obstacles for the penetration of white LEDs into the market for general illumination products. Mass production in terms of CoB, system in packaging (SiP), 3D packaging and wafer level packaging (WLP) can reduce the cost significantly, especially when chip cost is lowered by using a large wafer size.

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“…PSSs have been shown to effectively improve the LED efficiency. [7][8][9] Sapphire substrates can be patterned by several methods, including wet etching, 10,11 dry etching, 12,13 and nanoimprinting lithography. 14,15 .…”

Section: Introductionmentioning

confidence: 99%

Metal contact printing photolithography for fabrication of submicrometer patterned sapphire substrates for light-emitting diodes

Hsieh

Lee

2013

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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This paper reports an improved method that combines a metal film contact printing method with traditional photolithography for fabrication of submicrometer-scale patterned sapphire substrates (PSSs) used for high-brightness light-emitting diodes (LEDs). First, a patterned metal thin film is transferred from the surface of a mold onto a photoresist (PR) layer deposited on top of the sapphire substrate. The transferred metal pattern acts as a photomask for subsequent photolithographic processes. PR structures with a high aspect ratio of 5 and a small line width of 500 nm are fabricated on 2 and 4 in. sapphire wafers. Finally, inductively coupled plasma etching is performed on the sapphire substrates to obtain PSSs by using the patterned PR microstructures as an etching mask. Experiments have been performed and both 2 and 4 in. PSSs with submicrometer-scaled and cone-shaped surface features were successfully obtained. These PSSs can be used in the LED industry to obtain high-brightness LEDs.

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High Brightness GaN-Based Light-Emitting Diodes

Cited by 46 publications

References 21 publications

GaN-based light emitting diodes with embedded SiO2 pillars and air gap array structures

GaN-based light emitting diodes with embedded SiO2 pillars and air gap array structures

Status and prospects for phosphor-based white LED packaging

Metal contact printing photolithography for fabrication of submicrometer patterned sapphire substrates for light-emitting diodes

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