Improved light extraction efficiency of GaN-based vertical LEDs using hierarchical micro/subwavelength structures

Kang, Eun Kyu; Kwon, Eunhee; Min, Jung‐Wook; Song, Young Min; Lee, Yong Tak

doi:10.7567/jjap.54.06fh02

Cited by 7 publications

(4 citation statements)

References 31 publications

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“…(a) (b) These observations raise the questions of which light distribution related to the scattering or diffraction of the light caused by these textured structures would more greatly benefit LED light extraction, and what phenomenon is caused by the structures of the various dimensions of the microstructure, submicron structure, and nanostructure [20][21][22]. These are the main focuses of this paper.…”

Section: Preliminary Studymentioning

confidence: 99%

Scale-Dependent Light Scattering Analysis of Textured Structures on LED Light Extraction Enhancement Using Hybrid Full-Wave Finite-Difference Time-Domain and Ray-Tracing Methods

Lee

Chou

2017

Energies

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A multiscale model that enables quantitative understanding and prediction of the size effect on the scattering properties of micro-and nanostructures is crucial for the design of light-emitting diode (LED) surface textures optimized for high light extraction efficiency (LEE). In this paper, a hybrid process for combining full-wave finite-difference time-domain simulation and a ray-tracing technique based on a bidirectional scattering distribution function model is proposed. We apply this method to study the influence of different pattern sizes of a patterned sapphire substrate on GaN-based LED light extraction from the micro-scale to the nano-scale. The results show that near-wavelength-scale patterns with strong diffraction are not expected to enhance the LEE. By contrast, micro-scale patterns with optical diffusion behavior have the highest LEE at a specific aspect ratio, and subwavelength-scale patterns that have antireflection properties show a marked enhancement of the LEE for a wide range of aspect ratios.

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Section: Preliminary Studymentioning

confidence: 99%

Scale-Dependent Light Scattering Analysis of Textured Structures on LED Light Extraction Enhancement Using Hybrid Full-Wave Finite-Difference Time-Domain and Ray-Tracing Methods

Lee

Chou

2017

Energies

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“…What phenomenon is caused by the structures of the various dimensions of the microstructure, submicron structure, or nanostructure? [20][21][22] These are the main focuses of this paper. We hope to clarify and present solutions these questions with the establishment of the hybrid simulation approach.…”

Section: Preliminary Studymentioning

confidence: 99%

Scale-Dependent Light Scattering Analysis of Textured Structures on LED Light Extraction Enhancement Using Hybrid Full-Wave Finite-Difference Time-Domain and Ray-Tracing Methods

Lee¹,

Chou²

2017

Preprint

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A multiscale model that enables quantitative understanding and prediction of the size effect on scattering properties of micro-and nanostructures is crucial for the design of LED surface textures optimized for high light extraction efficiency (LEE). In this paper, a hybrid process for combining full-wave finite-difference time-domain simulation and a ray-tracing technique based on a bidirectional scattering distribution function model is proposed. We apply this method to study the influence of different pattern sizes of a patterned sapphire substrate on GaN-based LED light extraction from the microscale to the nanoscale. The results show that near-wavelength-scaled patterns with strong diffraction are not expected to enhance LEE. By contrast, microscaled patterns with optical diffusion behavior have the highest LEE at a specific aspect ratio, and subwavelengthscaled patterns that have antireflection properties show marked enhancement of LEE for a wide range of aspect ratios.

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“…However, only a few studies have reported on the integration of moth eye nanostructures across the entire surface of artificial cornea (i.e., microlens arrays). Previous studies on the hierarchical microand nanostructures mainly focused on the optical characteristics of each structure and important details related to the geometry of nanostructures were not optimized [9,10].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Disordered Subwavelength Structures on Curved Surfaces by Using a Thermal Dewetting Process

Lee¹,

Song²

2015

Applied Science and Convergence Technology

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We present disordered moth eye structures on curved surfaces fabricated by dry etching of thermally dewetted metal nanoparticles. This lithography-free fabrication allows the formation of subwavelength scale nanostructures on the strongly inclined surfaces such as ball lens as well as on the microlens arrays with low curvature. In particular, we found that the size and average distance of nanostructures are closely related to the inclined angle of the surface. Experimental results on oblique angle deposition of metal thin films followed by thermal dewetting also support these effects.

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Improved light extraction efficiency of GaN-based vertical LEDs using hierarchical micro/subwavelength structures

Cited by 7 publications

References 31 publications

Scale-Dependent Light Scattering Analysis of Textured Structures on LED Light Extraction Enhancement Using Hybrid Full-Wave Finite-Difference Time-Domain and Ray-Tracing Methods

Scale-Dependent Light Scattering Analysis of Textured Structures on LED Light Extraction Enhancement Using Hybrid Full-Wave Finite-Difference Time-Domain and Ray-Tracing Methods

Scale-Dependent Light Scattering Analysis of Textured Structures on LED Light Extraction Enhancement Using Hybrid Full-Wave Finite-Difference Time-Domain and Ray-Tracing Methods

Fabrication of Disordered Subwavelength Structures on Curved Surfaces by Using a Thermal Dewetting Process

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