The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Nelson Tansu - One of the best experts on this subject based on the ideXlab platform.
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fdtd analysis on Extraction Efficiency of gan light emitting diodes with microsphere arrays
IEEE\ OSA Journal of Display Technology, 2013Co-Authors: Peifen Zhu, Guangyu Liu, Jing Zhang, Nelson TansuAbstract:The improvement of light Extraction Efficiency of InGaN light-emitting diodes (LEDs) using microsphere arrays with various refractive indices was analyzed. Finite-difference time-domain (FDTD) simulations show that the use of microsphere (dmicrosphere = 500 nm) arrays with refractive indices of 1.8 and 2.5 led to increase in light Extraction Efficiency of InGaN LEDs by 1.9 times and 2.2 times, respectively. The enhancement in light Extraction Efficiency is attributed to the decrease in the Fresnel reflection and increase in effective photon escape cone due to graded refractive index and curvature formed between microsphere and free space. The maximum enhancement of light Extraction Efficiency of InGaN quantum well LEDs was achieved by employing the refractive index matched anatase-TiO2 microsphere arrays. The effects of microsphere diameters on the light Extraction Efficiency were also investigated and 2.4 times enhancement was achieved by employing 400-nm refractive index matched TiO2 sphere arrays.
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light Extraction Efficiency enhancement of ingan quantum wells light emitting diodes with polydimethylsiloxane concave microstructures
Optics Express, 2009Co-Authors: Yikkhoon Ee, Pisist Kumnorkaew, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
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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, 2009Co-Authors: Pisist Kumnorkaew, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
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Optimization of Light Extraction Efficiency of III-Nitride LEDs With Self-Assembled Colloidal-Based Microlenses
IEEE Journal of Selected Topics in Quantum Electronics, 2009Co-Authors: Pisist Kumnorkaew, Hongping Zhao, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
Hongping Zhao - One of the best experts on this subject based on the ideXlab platform.
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Light Extraction Efficiency enhancement for InGaN quantum wells light-emitting diodes with GaN micro-domes
Light-Emitting Diodes: Materials Devices and Applications for Solid State Lighting XVII, 2013Co-Authors: Peng Zhao, Lu Han, Hongping ZhaoAbstract:The enhancement of light Extraction Efficiency for thin-film-flip-chip (TFFC) InGaN QWs LEDs with GaN microdomes on n-GaN layer was studied. The three dimensional FDTD method was used to calculate the light Extraction Efficiency for the TFFC InGaN QWs LEDs emitting at visible spectral regime, as compared to that of the conventional TFFC InGaN QWs LEDs. The calculation indicates significant dependence of the p-GaN layer thickness on the light Extraction Efficiency. Significant enhancement of the light Extraction Efficiency (2.5-2.7 times for λpeak=460nm and 2.7- 2.8 times for λpeak=550nm) is achievable from LEDs with GaN micro-domes with optimized micro-dome diameter and height.
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Analysis of light Extraction Efficiency enhancement for thin-film-flip-chip InGaN quantum wells light-emitting diodes with GaN micro-domes
Optics Express, 2012Co-Authors: Peng Zhao, Hongping ZhaoAbstract:The enhancement of light Extraction Efficiency for thin-film flip-chip (TFFC) InGaN quantum wells (QWs) light-emitting diodes (LEDs) with GaN micro-domes on n-GaN layer was studied. The light Extraction Efficiency of TFFC InGaN QWs LEDs with GaN micro-domes were calculated and compared to that of the conventional TFFC InGaN QWs LEDs with flat surface. The three dimensional finite difference time domain (3D-FDTD) method was used to calculate the light Extraction Efficiency for the InGaN QWs LEDs emitting at 460nm and 550 nm, respectively. The effects of the GaN micro-dome feature size and the p-GaN layer thickness on the light Extraction Efficiency were studied systematically. Studies indicate that the p-GaN layer thickness is critical for optimizing the TFFC LED light Extraction Efficiency. Significant enhancement of the light Extraction Efficiency (2.5-2.7 times for λ(peak) = 460nm and 2.7-2.8 times for λ(peak) = 550nm) is achievable from TFFC InGaN QWs LEDs with optimized GaN micro-dome diameter and height.
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Analysis of light Extraction Efficiency enhancement for InGaN quantum wells light-emitting diodes with microspheres
2012 IEEE Energytech, 2012Co-Authors: Peng Zhao, Xuechen Jiao, Hongping ZhaoAbstract:The enhancement of light Extraction Efficiency for thin-film flip-chip (TFFC) InGaN quantum wells (QWs) light-emitting diodes (LEDs) with self-assembled microspheres on top of the n-GaN layer was studied. The light Extraction Efficiency of InGaN QWs LEDs for the three structures with 1) close-packed SiO 2 microlens; 2) close-packed SiO 2 /polystyrene microlens; and 3) GaN micro-hemispheres were calculated and compared to that of the conventional InGaN QWs LEDs with flat surface. Three dimensional finite difference time domain (3D-FDTD) method was used to calculate the light Extraction Efficiency for TFFC InGaN/GaN QWs LEDs emitting at 460nm. The effects of the microsphere/micro-hemisphere diameter and the p-GaN layer thickness on the light Extraction Efficiency were studied. Studies show that the p-GaN layer thickness is critical for optimizing the TFFC LED light Extraction Efficiency. Light Extraction Efficiency enhancement of 1.7 times and 1.85 times were obtained in the TFFC LEDs with SiO 2 microlens and SiO 2 /polystyrene microlens, respectively. More significant enhancement of the light Extraction Efficiency (>2.6 times) was achieved from LEDs with GaN micro-hemispheres with optimized micro-hemisphere diameter of D=1µm and p-GaN thickness of 195nm.
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Optimization of Light Extraction Efficiency of III-Nitride LEDs With Self-Assembled Colloidal-Based Microlenses
IEEE Journal of Selected Topics in Quantum Electronics, 2009Co-Authors: Pisist Kumnorkaew, Hongping Zhao, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
Pisist Kumnorkaew - One of the best experts on this subject based on the ideXlab platform.
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light Extraction Efficiency enhancement of ingan quantum wells light emitting diodes with polydimethylsiloxane concave microstructures
Optics Express, 2009Co-Authors: Yikkhoon Ee, Pisist Kumnorkaew, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
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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, 2009Co-Authors: Pisist Kumnorkaew, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
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Optimization of Light Extraction Efficiency of III-Nitride LEDs With Self-Assembled Colloidal-Based Microlenses
IEEE Journal of Selected Topics in Quantum Electronics, 2009Co-Authors: Pisist Kumnorkaew, Hongping Zhao, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
Ronald A Arif - One of the best experts on this subject based on the ideXlab platform.
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light Extraction Efficiency enhancement of ingan quantum wells light emitting diodes with polydimethylsiloxane concave microstructures
Optics Express, 2009Co-Authors: Yikkhoon Ee, Pisist Kumnorkaew, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
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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, 2009Co-Authors: Pisist Kumnorkaew, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
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Optimization of Light Extraction Efficiency of III-Nitride LEDs With Self-Assembled Colloidal-Based Microlenses
IEEE Journal of Selected Topics in Quantum Electronics, 2009Co-Authors: Pisist Kumnorkaew, Hongping Zhao, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
James F Gilchrist - One of the best experts on this subject based on the ideXlab platform.
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light Extraction Efficiency enhancement of ingan quantum wells light emitting diodes with polydimethylsiloxane concave microstructures
Optics Express, 2009Co-Authors: Yikkhoon Ee, Pisist Kumnorkaew, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
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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, 2009Co-Authors: Pisist Kumnorkaew, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
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Optimization of Light Extraction Efficiency of III-Nitride LEDs With Self-Assembled Colloidal-Based Microlenses
IEEE Journal of Selected Topics in Quantum Electronics, 2009Co-Authors: Pisist Kumnorkaew, Hongping Zhao, Ronald A Arif, Hua Tong, James F Gilchrist, Nelson TansuAbstract: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.
