InGaN light emitting diodes with a laser-treated tapered GaN structure

Huang, Wan-Chun; Lin, Chia−Feng; Hsieh, Tsung-Han; Chen, Sin-Han; Lin, Min‐Der; Chen, Kuei-Ting; Lin, Chun‐Min; Chen, Sy-Hann; Han, Pin

doi:10.1364/oe.19.0a1126

Cited by 8 publications

(3 citation statements)

References 19 publications

(20 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The patterned sapphire substrate (PSS) method has been reported to not only improve light extraction efficiency but also increase the internal light efficiency through a low dislocation effect when growing an epitaxial layer growth on the top of the sapphire substrate. [3][4][5][6] However, these studies are mostly based on lab experiments that are used to show if the efficiency is increased compared to the existing LEDs, which means the quantitative results are somewhat lacking. In order to quantitatively analyze the efficiency improvement from a PSS design, an LED has to pass through many processes.…”

Section: Introductionmentioning

confidence: 99%

Improving light-emitting diode performance through sapphire substrate double-side patterning

et al. 2013

View full text Add to dashboard Cite

Abstract. Here, we present a new double-side patterned sapphire substrate methodology that improves the efficiency of gallium nitride-light emitting diodes (GaN-LEDs). The light extraction efficiency of GaNbased LEDs was analyzed through the use of a ray-tracing simulation. The extraction efficiency was simulated using patterned sapphire substrate LEDs with a variety of shapes, depths, sizes, and spacing. Through the optimal patterning of the various factors, high extraction efficiency was realized and subsequently improved upon. The thermal LED characteristics were analyzed through the use of the COMSOL general heat transfer module. The LEDs patterned on the sapphire substrate were fabricated using nano imprint lithography. We found that the output power of the double-side patterned LED was 52% greater than that of a flat LED. The thermal resistance of the double side patterned LED was 9.5 K∕W less than that found for the flat LED. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

show abstract

Section: Introductionmentioning

confidence: 99%

Improving light-emitting diode performance through sapphire substrate double-side patterning

et al. 2013

View full text Add to dashboard Cite

show abstract

“…The largest reported wall-plug efficiency of 60% for GaN-based LEDs used a microroughened top surface, although the roughened surface morphology was irregular and uncontrolled. [4][5][6][7] In addition, it has been suggested from theoretical calculation that the external quantum efficiency of an LED chip can be as high as 70%-90% by incorporating a photonic crystal (PhC) structure. 8 Because of this, PhC LEDs are now being actively researched.…”

Section: Introductionmentioning

confidence: 99%

Enhanced light output from light emitting diodes with two-dimensional cone-shape nanostructured surface

Wang¹,

Chua²

2013

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

View full text Add to dashboard Cite

A simple, inexpensive and high throughput approach for creating two-dimensional cone-shaped nanostructures is reported. A self-assembled array of polystyrene nanospheres is employed as the primary mask to fabricate such structures on AlGaInP red light emitting diodes, resulting in over two times increase of light output power. An orderly array of cones show higher intensity emitted in the forward direction than one that is randomly arranged.

show abstract

“…Structures of InGaN-based LEDs that promote light extraction have also been formed using pulselaser fabrication processes. [10][11][12][13] Lee et al 14 increased the output power of an InGaN-based LED by reducing both the thermal damage to the sapphire substrate, along with the consequently formed debris, using femtosecond laser scribing.…”

mentioning

confidence: 99%

InGaN Light-Emitting Diodes with Embedded Roughened Structure in the GaN/Sapphire Interface Formed Using Laser Decomposition Process

Lin¹,

Huang²,

Chen³

et al. 2012

ECS J. Solid State Sci. Technol.

Self Cite

View full text Add to dashboard Cite

InGaN-based light-emitting diodes (LEDs) with inverted pyramidal structures at their GaN/patterned-sapphire interfaces were fabricated by laser decomposition and wet crystallographic etching. Partially roughening the LED structure increased the light output power of the by 21% enhancement at an operating current of 20mA over that of a non-treated LED structure. The transmittance of the roughened LED structure (10.5%) was lower than that of a non-treated LED structure (20.3%) at 447nm because the incident light was mostly reflected and scattered by the patterned-sapphire structure and by the roughened structure at the GaN/sapphire interface. The light emission intensity in the laser-treated striped region, with the roughened N-face GaN surface was higher than that in the non-treated patterned sapphire region. The InGaN structure with the roughened inverted pyramidal structure increased the light extraction efficiency of nitride-based LEDs.Gallium nitride materials have attracted much interest in the development of optoelectronic devices such as white light-emitting diodes 1 (LEDs) and laser diodes. Nevertheless, bright blue LEDs require higher internal and external quantum efficiencies. The low external quantum efficiency of InGaN-based LEDs is caused by the large difference between the refractive indexes of the GaN layer and the surrounding air ( n∼1.5). Bottom-patterned Al 2 O 3 substrates, 2 roughened p-type GaN:Mg surface, 3 the formation of photonic crystal structures, 4 amorphous titanium oxide films with porous structures and a graded refractive-index, 5 two-floor air prism arrays as embedded reflectors, 6 overcut side-holes that are formed by wet etching, 7 and anisotropically etched GaN-sapphire interfaces, 8 have all been utilized to increase the light-extraction efficiency of InGaN-based LEDs on Al 2 O 3 substrates. Fujii et al. 9 reported that a laser-lift-off technique that was followed by an anisotropic etching process to roughen the surface of an n-side-up GaN-based LED with a hexagonal ''conelike'' surface, increased extraction efficiency. Structures of InGaN-based LEDs that promote light extraction have also been formed using pulselaser fabrication processes. 10-13 Lee et al. 14 increased the output power of an InGaN-based LED by reducing both the thermal damage to the sapphire substrate, along with the consequently formed debris, using femtosecond laser scribing.In this work, roughened inverted-pyramidal structures of InGaN LEDs were observed at the top and the bottom of the patternedsapphire substrate via a laser decomposition process and a wet etching process. The InGaN LED structure comprised a patterned sapphire substrate and a roughened structure that increased light extraction efficiency. A roughened N-face GaN surface was formed for high light extraction without using a conventional laser lift-off process. The optical properties, light-extraction efficiency, and far-field radiation pattern of the laser-treated LED structures were analyzed in detail. ExperimentalInGaN-based LED structures w...

show abstract

InGaN light emitting diodes with a laser-treated tapered GaN structure

Cited by 8 publications

References 19 publications

Improving light-emitting diode performance through sapphire substrate double-side patterning

Improving light-emitting diode performance through sapphire substrate double-side patterning

Enhanced light output from light emitting diodes with two-dimensional cone-shape nanostructured surface

InGaN Light-Emitting Diodes with Embedded Roughened Structure in the GaN/Sapphire Interface Formed Using Laser Decomposition Process

Contact Info

Product

Resources

About