Enhanced Light Output in Roughened GaN-Based Light-Emitting Diodes Using Electrodeless Photoelectrochemical Etching

Hsu, Shun-Cheng; Lee, Chong−Yi; Hwang, Jung-Min; Su, Juh-Yuh; Wuu, Dong−Sing; Horng, Ray−Hua

doi:10.1109/lpt.2006.886862

Cited by 9 publications

(4 citation statements)

References 10 publications

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“…일반적인 LED에서 방출되는 빛은 생성된 빛의 극히 일부분에 지나지 않으며 대부분의 빛은 LED 외부로 방 출되지 못하고 내부에 갇히게 되어 LED의 광 추출 효율은 낮을 수 밖에 없다 [3] . 적 요철구조를 만드는 텍스처링(texturing) 기술 [4] , 나노 형상 의 주기적 패턴인 포토닉 크리스탈(photonic crystal) 기술 [5] , 사파이어(sapphire) 기판의 표면에 주기적인 요철을 가공한 사파이어 가공기판 (patterned sapphire substrate) 기술 [6] , 매 우 얇은 금속 막을 이용한 표면 플라즈몬 (surface plasmon) 기술 [7] …”

Section: 서 론 발광 다이오드(Led)는 기존의 여러 광원들을 대체할 차세 대 광원으로써 조명 자동차 의료unclassified

A Study of the Upper Layer for Improvement of the Extraction Efficiency in LED

최철현¹,

이동진²,

임해동³

et al. 2011

Korean Journal of Optics and Photonics

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In this paper, we improved the light extraction efficiency by considering an additional upper layer on the top surface of a conventional LED. We simulated the LED's light emission as functions of the thickness and the refractive index of the upper layer, and analyzed how the condition improved the light efficiency. When the refractive index's range was from 1.05 to 1.40, the LED emission increased. For that case, the emission also increased as the thickness increased. We experimentally showed that the light extraction efficiency was improved about 22% by forming the upper layer on the top surface of an LED using material with refractive index 1.30 at 589.3 nm. It is expected that forming the upper layer on an LED can easily improve the extraction efficiency.

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Section: 서 론 발광 다이오드(Led)는 기존의 여러 광원들을 대체할 차세 대 광원으로써 조명 자동차 의료unclassified

A Study of the Upper Layer for Improvement of the Extraction Efficiency in LED

최철현¹,

이동진²,

임해동³

et al. 2011

Korean Journal of Optics and Photonics

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“…Studies conducted on LEDs have revealed that light extraction efficiency can be improved by a surface treatment such as moth-eye processing on the substrate, which increases light intensity. [20][21][22][23][24][25][26][27][28][29][30] Therefore, to increase the photosensitivity of AlGaN= AlGaN HFET sensors, specific surface structures were investigated. It was previously reported that the initial growth of p-type GaN on an AlN layer results in the formation of three-dimensional island crystals, even when p-type GaN is grown on AlGaN using a high AlN molar fraction.…”

Section: Introductionmentioning

confidence: 99%

Realization of high-performance hetero-field-effect-transistor-type ultraviolet photosensors using p-type GaN comprising three-dimensional island crystals

Yamamoto

Yoshikawa

Kusafuka

et al. 2016

Jpn. J. Appl. Phys.

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High-performance AlGaN/AlGaN hetero-field-effect-transistor (HFET)-type photosensors with high photosensitivity were fabricated using p-type GaN comprising three-dimensional island crystals. The p-type GaN layers were grown on AlGaN layers at a high AlN molar fraction, and the area of p-type GaN comprising three-dimensional island crystals increased as the thickness of the p-type GaN film decreased, resulting in a reduced p-type GaN coverage ratio. The p-type GaN layers comprising three-dimensional island crystals and showing low coverage ratios were then used to fabricate HFET-type photosensors with high photosensitivity. A high light sensitivity of 1.5 × 104 A/W was obtained at a source–drain voltage (V SD) of 0.5 V for a photosensor with a p-type GaN thickness of 20 nm. Moreover, the dark current was suppressed to 10−10 A/mm and the photosensor achieved an extremely high photocurrent to dark current density ratio.

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“…Photonic crystal structures, 2,3 a nanorod structure, 4 a pattern sapphire structure, 5 microdisk and microring cavities, 6,7 photoelectrochemically treated microhole-array pattern, 8 embedded air protrusions 9 and air void structure, 10 and textured sidewalls 11 have all been used to increase light extraction efficiency in InGaN-based LEDs on Al 2 O 3 substrates. A photoelectrochemical (PEC) wet etching technique 12,13,14,15 applied on GaN-based materials has been used to fabricate the roughened surface and to increase the light extraction efficiency.…”

mentioning

confidence: 99%

Nitride-Based Light-Emitting Diodes with a Radiated-Cone-Shaped Structure at GaN/Sapphire Interface

Lin

Chen

et al. 2012

ECS J. Solid State Sci. Technol.

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InGaN-based light-emitting diode (LED) with a radiated-cone-shaped structure at GaN/sapphire interface was fabricated through a laser drilling process and a photoelectrochemical (PEC) wet etching process. The inverted cone-shaped GaN structure was formed around the laser-drilled hole as a light scattering structure to enhance the light extraction efficiency at central mesa region. The light output power of the PEC-treated LED structure had an approximate 19% enhancement when compared to a conventional LED at 20 mA. The photoluminescence peak wavelength of the InGaN active layer was slightly blueshifted from 458.4 nm for the conventional LED to 449.9 nm for the treated-LED that could be caused by partially reducing the compressive strain induced piezoelectric field by forming the radiated-cone-shaped structure at GaN/sapphire interface. High light emission intensity for the treated LED structure was observed around the laser-drilled hole pattern as a result of a higher light-scattering process occurring at the radiated-cone-shaped structure for the InGaN-based LED applications.

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Enhanced Light Output in Roughened GaN-Based Light-Emitting Diodes Using Electrodeless Photoelectrochemical Etching

Cited by 9 publications

References 10 publications

A Study of the Upper Layer for Improvement of the Extraction Efficiency in LED

A Study of the Upper Layer for Improvement of the Extraction Efficiency in LED

Realization of high-performance hetero-field-effect-transistor-type ultraviolet photosensors using p-type GaN comprising three-dimensional island crystals

Nitride-Based Light-Emitting Diodes with a Radiated-Cone-Shaped Structure at GaN/Sapphire Interface

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