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Ching-cherng Sun - One of the best experts on this subject based on the ideXlab platform.

  • Light Extraction enhancement of GaN-based LEDs through passive/active photon recycling
    Optics Communications, 2011
    Co-Authors: Ching-cherng Sun, Tsung-xian Lee, Cheng-chien Chen, Shang-yu Tsai
    Abstract:

    Abstract In this paper, we present a study of Light Extraction of GaN-based LEDs through active/passive photon recycling, including sapphire-based and Thin-GaN based on Monte Carlo ray tracing. The mechanisms in enhancing Light Extraction incorporated with implanting micro pyramid (lens) array and lens encapsulation of both cavity photon recycling and quantum photon recycling are discussed. For an absorption coefficient of 200 cm− 1 in the active layer, both approaches perform more than 90% of Light Extraction efficiency through cavity photon recycling. For a heavy absorbed active layer, the quantum photon recycling could play an important role in Light Extraction.

  • Light Extraction analysis of gan based Light emitting diodes with surface texture and or patterned substrate
    Optics Express, 2007
    Co-Authors: Tsung-xian Lee, Ko-fon Gao, Wei-ting Chien, Ching-cherng Sun
    Abstract:

    Light Extraction analysis of GaN-based Light-emitting diodes (LEDs) with Monte Carlo ray tracing is presented. To obtain high Light Extraction efficiency, periodic structures introduced on the top surface and/or on the substrate of various types of LED are simulated, including wire bonding, flip chip and Thin GaN. Micro pyramid array with an apex angle from 20° to 70° is shown to effectively improve the Light Extraction efficiency. In addition, for an LED encapsulated within an epoxy lens, the patterned substrate with pyramid array is found to be a more effective way to increase Light Extraction efficiency than the surface texture.

  • Light Extraction analysis of GaN-based Light-emitting diodes with surface texture and/or patterned substrate.
    Optics express, 2007
    Co-Authors: Tsung-xian Lee, Ko-fon Gao, Wei-ting Chien, Ching-cherng Sun
    Abstract:

    Light Extraction analysis of GaN-based Light-emitting diodes (LEDs) with Monte Carlo ray tracing is presented. To obtain high Light Extraction efficiency, periodic structures introduced on the top surface and/or on the substrate of various types of LED are simulated, including wire bonding, flip chip and Thin GaN. Micro pyramid array with an apex angle from 20o to 70o is shown to effectively improve the Light Extraction efficiency. In addition, for an LED encapsulated within an epoxy lens, the patterned substrate with pyramid array is found to be a more effective way to increase Light Extraction efficiency than the surface texture.

  • Light Extraction analysis of GaN-based LEDs
    2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006
    Co-Authors: Tsung-xian Lee, Wei-ting Chien, Ching-cherng Sun
    Abstract:

    Light Extraction efficiency of GaN-based LEDs as functions of chip dimensions, absorption coefficients and package for both conventional one and Thin-GaN are analyzed based on Monte-Carlo ray tracing.

  • Analysis of position-dependent Light Extraction of GaN-based LEDs
    Optics Express, 2005
    Co-Authors: Tsung-xian Lee, Chao-ying Lin, Shih Hsin Ma, Ching-cherng Sun
    Abstract:

    The Light Extraction efficiency of GaN-based LEDs as a function of the position of the Light source over the active layer is studied. Several parameters, including chip dimensions, absorption coefficients and package are analyzed on the basis of a Monte-Carlo ray tracing simulation. The Light Extraction efficiency of a Thin-GaN LED is studied with respect to a sapphire-based LED, including the surface texture.

Tsung-xian Lee - One of the best experts on this subject based on the ideXlab platform.

  • Light Extraction enhancement of GaN-based LEDs through passive/active photon recycling
    Optics Communications, 2011
    Co-Authors: Ching-cherng Sun, Tsung-xian Lee, Cheng-chien Chen, Shang-yu Tsai
    Abstract:

    Abstract In this paper, we present a study of Light Extraction of GaN-based LEDs through active/passive photon recycling, including sapphire-based and Thin-GaN based on Monte Carlo ray tracing. The mechanisms in enhancing Light Extraction incorporated with implanting micro pyramid (lens) array and lens encapsulation of both cavity photon recycling and quantum photon recycling are discussed. For an absorption coefficient of 200 cm− 1 in the active layer, both approaches perform more than 90% of Light Extraction efficiency through cavity photon recycling. For a heavy absorbed active layer, the quantum photon recycling could play an important role in Light Extraction.

  • Improvement in Light Extraction efficiency of high brightness InGaN-based Light emitting diodes
    Gallium Nitride Materials and Devices IV, 2009
    Co-Authors: Tzer-perng Chen, Ta-cheng Hsu, Chuan-yu Luo, Ming-chi Hsu, Tsung-xian Lee
    Abstract:

    Light Extraction efficiency is important to the brightness of LEDs. In this study, various texturing and roughing schemes were formed on the surface or interface of InGaN-based LED structure grown on sapphire substrate to investigate their effects. Throughout the research, temperature-dependent PL measurement was used to calculate the internal quantum efficiency so as to derive the Light Extraction efficiency. The Light Extraction efficiency is around 60 to 65% while the epitaxy and substrate are flat. On the other hand, the Light Extraction efficiency reaches an optimal value of around 85% while the p-GaN surface is textured and the substrate is patterned. However, for LED having only one-side surface texturing structure optimized on either p- or n-side, the Light Extraction efficiency can be already as high as 75 to 80%. Methods for further enhancement, such as use of ZnO nanorod on chip surface, were also discussed.

  • Light Extraction analysis of gan based Light emitting diodes with surface texture and or patterned substrate
    Optics Express, 2007
    Co-Authors: Tsung-xian Lee, Ko-fon Gao, Wei-ting Chien, Ching-cherng Sun
    Abstract:

    Light Extraction analysis of GaN-based Light-emitting diodes (LEDs) with Monte Carlo ray tracing is presented. To obtain high Light Extraction efficiency, periodic structures introduced on the top surface and/or on the substrate of various types of LED are simulated, including wire bonding, flip chip and Thin GaN. Micro pyramid array with an apex angle from 20° to 70° is shown to effectively improve the Light Extraction efficiency. In addition, for an LED encapsulated within an epoxy lens, the patterned substrate with pyramid array is found to be a more effective way to increase Light Extraction efficiency than the surface texture.

  • Light Extraction analysis of GaN-based Light-emitting diodes with surface texture and/or patterned substrate.
    Optics express, 2007
    Co-Authors: Tsung-xian Lee, Ko-fon Gao, Wei-ting Chien, Ching-cherng Sun
    Abstract:

    Light Extraction analysis of GaN-based Light-emitting diodes (LEDs) with Monte Carlo ray tracing is presented. To obtain high Light Extraction efficiency, periodic structures introduced on the top surface and/or on the substrate of various types of LED are simulated, including wire bonding, flip chip and Thin GaN. Micro pyramid array with an apex angle from 20o to 70o is shown to effectively improve the Light Extraction efficiency. In addition, for an LED encapsulated within an epoxy lens, the patterned substrate with pyramid array is found to be a more effective way to increase Light Extraction efficiency than the surface texture.

  • Light Extraction analysis of GaN-based LEDs
    2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006
    Co-Authors: Tsung-xian Lee, Wei-ting Chien, Ching-cherng Sun
    Abstract:

    Light Extraction efficiency of GaN-based LEDs as functions of chip dimensions, absorption coefficients and package for both conventional one and Thin-GaN are analyzed based on Monte-Carlo ray tracing.

Wei-ming Lin - One of the best experts on this subject based on the ideXlab platform.

  • Organic Light-emitting diodes fabricated on recessed anodes for Light Extraction enhancement
    Organic Electronics, 2015
    Co-Authors: Ching-ming Hsu, Yin-xing Zeng, Bo-ting Lin, Wei-ming Lin
    Abstract:

    Abstract Circular recesses have been fabricated on indium tin oxide (ITO) anodes to enhance Light Extraction of organic Light-emitting diodes (OLEDs). The effects of recess depth and recess coverage ratio on the performance of a green OLED were systematically investigated. Results showed that the current efficiency could be enhanced from 40.7 cd/A of a planar device to 47.2 cd/A of the device with a recess depth of 100 nm and a recess coverage ratio of 14.1%. The enhanced Light Extraction by the recess wall effect was realized to be the major factor leading to the improved efficiency. The efficiency is however limited by the accompanying increase in electrical resistivity of the ITO films at deep recesses and high recess coverage ratios. Despite of the insignificant efficiency enhancement (up to 16%) in this study, this recessed ITO approach provides a simple architecture to enhance waveguide mode Light Extraction without adding an internal medium.

  • Enhanced Light Extraction of organic Light-emitting diodes using recessed anodes
    Applied Surface Science, 2014
    Co-Authors: Ching-ming Hsu, Yin-xing Zeng, Bo-ting Lin, Wei-ming Lin
    Abstract:

    Abstract Recessed indium tin oxide films were prepared to serve as anodes for enhancing Light Extraction efficiency of organic Light-emitting diodes (OLEDs). The power efficiency of OLEDs with the proposed films was enhanced by up to 28%. This improvement can be attributed to enhanced Light Extraction due to the wall effect and the bottom scattering effect of the recesses. The power efficiency increased with recess depth but was limited by the accompanying high electrical resistivity and large optical loss.

Nelson Tansu - One of the best experts on this subject based on the ideXlab platform.

  • Light Extraction efficiency enhancement of ingan quantum wells Light emitting diodes with polydimethylsiloxane concave microstructures
    Optics Express, 2009
    Co-Authors: Yikkhoon Ee, Pisist Kumnorkaew, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson Tansu
    Abstract:

    Improvement of Light Extraction efficiency of InGaN Light emitting diodes (LEDs) using polydimethylsiloxane (PDMS) concave microstructures arrays was demonstrated. The size effect of the concave microstructures on the Light Extraction efficiency of III-Nitride LEDs was studied. Depending on the size of the concave microstructures, ray tracing simulations show that the use of PDMS concave microstructures arrays can lead to increase in Light Extraction efficiency of InGaN LEDs by 1.5 to 2.0 times. Experiments utilizing 2.0 micro n thick PDMS with 1.0 micron diameter of the PDMS concave microstructures arrays demonstrated 1.70 times improvement in Light Extraction efficiency, which is consistent with improvement of 1.77 times predicted from simulation. The enhancement in Light Extraction efficiency is attributed to increase in effective photon escape cone due to PDMS concave microstructures arrays.

  • Enhancement of Light Extraction efficiency of InGaN quantum well Light-emitting diodes with polydimethylsiloxane concave microstructures
    Light-Emitting Diodes: Materials Devices and Applications for Solid State Lighting XIII, 2009
    Co-Authors: Pisist Kumnorkaew, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson Tansu
    Abstract:

    Improvement of Light Extraction efficiency of InGaN Light emitting diodes (LEDs) using polydimethylsiloxane (PDMS) concave microstructures arrays was demonstrated. The size effect of the concave microstructures on the Light Extraction efficiency of III-Nitride LEDs was studied. Depending on the size of the concave microsturctures, ray tracing simulations show that the use of PDMS concave microstructures arrays can lead to increase in Light Extraction efficiency of InGaN LEDs by 1.4 to 1.9 times. Experiments utilizing 1.0 μm PDMS concave microstructures arrays demonstrated 1.60 times improvement in Light Extraction, which is consistent with simulated improvement of 1.63 times. The enhancement in Light Extraction efficiency is attributed to increase in effective photon escape cone due to PDMS concave microstructures arrays, and reduced Fresnel reflection within the photon escape cone due to the grading of refractive index change between GaN / PDMS / air interface.

  • Optimization of Light Extraction Efficiency of III-Nitride LEDs With Self-Assembled Colloidal-Based Microlenses
    IEEE Journal of Selected Topics in Quantum Electronics, 2009
    Co-Authors: Pisist Kumnorkaew, Hongping Zhao, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson Tansu
    Abstract:

    Improvement of Light Extraction efficiency of InGaN LEDs using colloidal-based SiO2/polystyrene (PS) microlens arrays was demonstrated. The size effect of the SiO2 microspheres and the thickness effect of the PS layer on the Light Extraction efficiency of III-nitride LEDs were studied. The monolayer rapid convective deposition conditions for SiO2 microspheres were also investigated. Ray tracing simulations show that the use of microlens arrays can lead to increase in Light Extraction efficiency of InGaN LEDs by 2.64 times. This is consistent with experiments that demonstrated 2.49 times improvement in Light Extraction utilizing SiO2/PS microlens arrays. The enhancement in Light Extraction efficiency is attributed to increase in effective photon escape cone due to SiO2/PS microlens arrays, and reduced Fresnel reflection within the photon escape cone due to the grading of refractive index change between GaN/SiO2/PS/air interface.

Wei-ting Chien - One of the best experts on this subject based on the ideXlab platform.

  • Light Extraction analysis of gan based Light emitting diodes with surface texture and or patterned substrate
    Optics Express, 2007
    Co-Authors: Wei-ting Chien
    Abstract:

    Light Extraction analysis of GaN-based Light-emitting diodes (LEDs) with Monte Carlo ray tracing is presented. To obtain high Light Extraction efficiency, periodic structures introduced on the top surface and/or on the substrate of various types of LED are simulated, including wire bonding, flip chip and Thin GaN. Micro pyramid array with an apex angle from 20° to 70° is shown to effectively improve the Light Extraction efficiency. In addition, for an LED encapsulated within an epoxy lens, the patterned substrate with pyramid array is found to be a more effective way to increase Light Extraction efficiency than the surface texture.

  • Light Extraction analysis of gan based Light emitting diodes with surface texture and or patterned substrate
    Optics Express, 2007
    Co-Authors: Tsung-xian Lee, Ko-fon Gao, Wei-ting Chien, Ching-cherng Sun
    Abstract:

    Light Extraction analysis of GaN-based Light-emitting diodes (LEDs) with Monte Carlo ray tracing is presented. To obtain high Light Extraction efficiency, periodic structures introduced on the top surface and/or on the substrate of various types of LED are simulated, including wire bonding, flip chip and Thin GaN. Micro pyramid array with an apex angle from 20° to 70° is shown to effectively improve the Light Extraction efficiency. In addition, for an LED encapsulated within an epoxy lens, the patterned substrate with pyramid array is found to be a more effective way to increase Light Extraction efficiency than the surface texture.

  • Light Extraction analysis of GaN-based Light-emitting diodes with surface texture and/or patterned substrate.
    Optics express, 2007
    Co-Authors: Tsung-xian Lee, Ko-fon Gao, Wei-ting Chien, Ching-cherng Sun
    Abstract:

    Light Extraction analysis of GaN-based Light-emitting diodes (LEDs) with Monte Carlo ray tracing is presented. To obtain high Light Extraction efficiency, periodic structures introduced on the top surface and/or on the substrate of various types of LED are simulated, including wire bonding, flip chip and Thin GaN. Micro pyramid array with an apex angle from 20o to 70o is shown to effectively improve the Light Extraction efficiency. In addition, for an LED encapsulated within an epoxy lens, the patterned substrate with pyramid array is found to be a more effective way to increase Light Extraction efficiency than the surface texture.

  • Light Extraction analysis of GaN-based LEDs
    2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006
    Co-Authors: Tsung-xian Lee, Wei-ting Chien, Ching-cherng Sun
    Abstract:

    Light Extraction efficiency of GaN-based LEDs as functions of chip dimensions, absorption coefficients and package for both conventional one and Thin-GaN are analyzed based on Monte-Carlo ray tracing.