Abstract

This paper presents a novel and mass-producible technique to fabricate indium-tin-oxide (ITO) nanorods which serve as an omnidirectional transparent conductive layer (TCL) for InGaN/GaN light emitting diodes (LEDs). The characteristic nanorods, prepared by oblique electron-beam evaporation in a nitrogen ambient, demonstrate high optical transmittance (T>90%) for the wavelength range of 450nm to 900nm. The light output power of a packaged InGaN/GaN LED with the incorporated nanorod layer is increased by 35.1% at an injection current of 350mA, compared to that of a conventional LED. Calculations based on a finite difference time domain (FDTD) method suggest that the extraction enhancement factor can be further improved by increasing the thickness of the nanorod layer, indicating great potential to enhance the luminous intensity of solid-state lighting devices using ITO nanorod structures.

© 2009 OSA

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    [CrossRef]
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    [CrossRef]
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    [CrossRef] [PubMed]

2009 (1)

P. Yu, C. H. Chang, C. H. Chiu, C. S. Yang, J. C. Yu, H. C. Kuo, S. H. Hsu, and Y. C. Chang, “Efficiency Enhancement of GaAs Photovoltaics Employing Anti-Reflective Indium-Tin-Oxide Nano-Columns,” Adv. Mater. 21(16), 1618–1621 (2009).
[CrossRef]

2008 (5)

C. H. Chiu, P. Yu, H. C. Kuo, C. C. Chen, T. C. Lu, S. C. Wang, S. H. Hsu, Y. J. Cheng, and Y. C. Chang, “Broadband and omnidirectional antireflection employing disordered GaN nanopillars,” Opt. Express 16(12), 8748–8754 (2008).
[CrossRef] [PubMed]

J. H. Lee, J. T. Oh, Y. C. Kim, and J. H. Lee, “Stress Reduction and Enhanced Extraction Efficiency of GaN-Based LED Grown on Cone-Shape-Patterned Sapphire,” IEEE Photon. Technol. Lett. 20(18), 1563–1565 (2008).
[CrossRef]

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

F. Ishida, K. Yoshimura, K. Hoshino, and K. Tadatomo, “Improved light extraction efficiency of GaN-based light emitting diodes by using needle-shape indium tin oxide p-contact,” Phys. Status Solidi 5(6 c), 2083–2085 (2008).
[CrossRef]

J. K. Kim, S. Chhajed, M. F. Schubert, E. F. Schubert, A. J. Fischer, M. H. Crawford, J. Cho, H. Kim, and C. Sone, “Light-Extraction Enhancement of GaInN Light-Emitting Diodes by Graded-Refractive-Index Indium Tin Oxide Anti-Reflection Contact,” Adv. Mater. 20(4), 801–804 (2008).
[CrossRef]

2007 (3)

S. Takaki, Y. Aoshima, and R. Satoh, “Growth Mechanism of Indium Tin Oxide Whiskers Prepared by Sputtering,” J. Appl. Phys. 46(No. 6A), 3537–3544 (2007).
[CrossRef]

J. Zhong, H. Chen, G. Saraf, Y. Lu, C. K. Choi, J. J. Song, D. M. Mackie, and H. Shen, “Integrated ZnO nanotips on GaN light emitting diodes for enhanced emission efficiency,” Appl. Phys. Lett. 90(20), 203515 (2007).
[CrossRef]

C. H. Chiu, H. C. Kuo, C. E. Lee, C. H. Lin, P. C. Cheng, H. W. Huang, T. C. Lu, S. C. Wang, and K. M. Leung, “Fabrication and characteristics of thin-film InGaN–GaN light-emitting diodes with TiO2/SiO2 omnidirectional reflectors,” Semicond. Sci. Technol. 22(7), 831–835 (2007).
[CrossRef]

2006 (2)

R. H. Horng, S. H. Huang, C. C. Yang, and D. S. Wuu, “Efficiency Improvement of GaN-Based LEDs with ITO Texturing Window Layers Using Natural Lithography,” IEEE J. Sel. Top. Quantum Electron. 12(6), 1196–1201 (2006).
[CrossRef]

Y. J. Lee, J. M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Photon. Technol. Lett. 18(10), 1152–1154 (2006).
[CrossRef]

2005 (4)

D. W. Kim, H. Y. Lee, M. C. Yoo, and G. Y. Yeom, “Highly efficient vertical laser-liftoff GaN-based light-emitting diodes formed by optimization of the cathode structure,” Appl. Phys. Lett. 86(5), 052108 (2005).
[CrossRef]

H. W. Huang, C. C. Kao, J. T. Chu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Improvement of InGaN–GaN light-emitting diode performance with a nano-roughened p-GaN surface,” IEEE Photon. Technol. Lett. 17(5), 983–985 (2005).
[CrossRef]

H. W. Huang, J. T. Chu, C. C. Kao, T. H. Hseuh, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Enhanced light output of an InGaN/GaN light emitting diode with a nano-roughened p-GaN surface,” Nanotechnology 16(9), 1844–1848 (2005).
[CrossRef]

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

2004 (1)

T. Fujii, Y. Gao, R. Sharma, E. L. Hu, S. P. DenBaars, and S. Nakamura, “Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening,” Appl. Phys. Lett. 84(6), 855–857 (2004).
[CrossRef]

2002 (1)

Y. Narukawa, I. Niki, K. Izuno, M. Yamada, Y. Murazaki, and T. Mukai, “Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip,” J. Appl. Phys. 41(Part 2, No. 4A), L371–L373 (2002).

1998 (1)

J. Han, M. H. Crawford, R. J. Shul, J. J. Figiel, M. Banas, L. Zhang, Y. K. Song, H. Zhou, and A. V. Nurmikko, “AlGaN/GaN quantum well ultraviolet light emitting diodes,” Appl. Phys. Lett. 73(12), 1688 (1998).
[CrossRef]

1970 (1)

H. Hashimoto, A. Kumao, T. Eto, and K. Fujiwara, “Drops of oxides on tungsten oxide needles and nuclei of dendritic crystals,” J. Cryst. Growth 7(1), 113–116 (1970).
[CrossRef]

1968 (1)

H. Hashimoto, T. Naiki, T. Eto, and K. Fujiwara, “High Temperature Gas Reaction Specimen Chamber for an Electron Microscope,” J. Appl. Phys. 7(8), 946–952 (1968).
[CrossRef]

Aoshima, Y.

S. Takaki, Y. Aoshima, and R. Satoh, “Growth Mechanism of Indium Tin Oxide Whiskers Prepared by Sputtering,” J. Appl. Phys. 46(No. 6A), 3537–3544 (2007).
[CrossRef]

Banas, M.

J. Han, M. H. Crawford, R. J. Shul, J. J. Figiel, M. Banas, L. Zhang, Y. K. Song, H. Zhou, and A. V. Nurmikko, “AlGaN/GaN quantum well ultraviolet light emitting diodes,” Appl. Phys. Lett. 73(12), 1688 (1998).
[CrossRef]

Chang, C. H.

P. Yu, C. H. Chang, C. H. Chiu, C. S. Yang, J. C. Yu, H. C. Kuo, S. H. Hsu, and Y. C. Chang, “Efficiency Enhancement of GaAs Photovoltaics Employing Anti-Reflective Indium-Tin-Oxide Nano-Columns,” Adv. Mater. 21(16), 1618–1621 (2009).
[CrossRef]

Chang, Y. C.

P. Yu, C. H. Chang, C. H. Chiu, C. S. Yang, J. C. Yu, H. C. Kuo, S. H. Hsu, and Y. C. Chang, “Efficiency Enhancement of GaAs Photovoltaics Employing Anti-Reflective Indium-Tin-Oxide Nano-Columns,” Adv. Mater. 21(16), 1618–1621 (2009).
[CrossRef]

C. H. Chiu, P. Yu, H. C. Kuo, C. C. Chen, T. C. Lu, S. C. Wang, S. H. Hsu, Y. J. Cheng, and Y. C. Chang, “Broadband and omnidirectional antireflection employing disordered GaN nanopillars,” Opt. Express 16(12), 8748–8754 (2008).
[CrossRef] [PubMed]

Chao, C. L.

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

Chen, C. C.

Chen, H.

J. Zhong, H. Chen, G. Saraf, Y. Lu, C. K. Choi, J. J. Song, D. M. Mackie, and H. Shen, “Integrated ZnO nanotips on GaN light emitting diodes for enhanced emission efficiency,” Appl. Phys. Lett. 90(20), 203515 (2007).
[CrossRef]

Chen, S. Y.

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

Cheng, B. S.

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

Cheng, P. C.

C. H. Chiu, H. C. Kuo, C. E. Lee, C. H. Lin, P. C. Cheng, H. W. Huang, T. C. Lu, S. C. Wang, and K. M. Leung, “Fabrication and characteristics of thin-film InGaN–GaN light-emitting diodes with TiO2/SiO2 omnidirectional reflectors,” Semicond. Sci. Technol. 22(7), 831–835 (2007).
[CrossRef]

Cheng, Y. J.

Chhajed, S.

J. K. Kim, S. Chhajed, M. F. Schubert, E. F. Schubert, A. J. Fischer, M. H. Crawford, J. Cho, H. Kim, and C. Sone, “Light-Extraction Enhancement of GaInN Light-Emitting Diodes by Graded-Refractive-Index Indium Tin Oxide Anti-Reflection Contact,” Adv. Mater. 20(4), 801–804 (2008).
[CrossRef]

Chiu, C. H.

P. Yu, C. H. Chang, C. H. Chiu, C. S. Yang, J. C. Yu, H. C. Kuo, S. H. Hsu, and Y. C. Chang, “Efficiency Enhancement of GaAs Photovoltaics Employing Anti-Reflective Indium-Tin-Oxide Nano-Columns,” Adv. Mater. 21(16), 1618–1621 (2009).
[CrossRef]

C. H. Chiu, P. Yu, H. C. Kuo, C. C. Chen, T. C. Lu, S. C. Wang, S. H. Hsu, Y. J. Cheng, and Y. C. Chang, “Broadband and omnidirectional antireflection employing disordered GaN nanopillars,” Opt. Express 16(12), 8748–8754 (2008).
[CrossRef] [PubMed]

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

C. H. Chiu, H. C. Kuo, C. E. Lee, C. H. Lin, P. C. Cheng, H. W. Huang, T. C. Lu, S. C. Wang, and K. M. Leung, “Fabrication and characteristics of thin-film InGaN–GaN light-emitting diodes with TiO2/SiO2 omnidirectional reflectors,” Semicond. Sci. Technol. 22(7), 831–835 (2007).
[CrossRef]

Cho, J.

J. K. Kim, S. Chhajed, M. F. Schubert, E. F. Schubert, A. J. Fischer, M. H. Crawford, J. Cho, H. Kim, and C. Sone, “Light-Extraction Enhancement of GaInN Light-Emitting Diodes by Graded-Refractive-Index Indium Tin Oxide Anti-Reflection Contact,” Adv. Mater. 20(4), 801–804 (2008).
[CrossRef]

Choi, C. K.

J. Zhong, H. Chen, G. Saraf, Y. Lu, C. K. Choi, J. J. Song, D. M. Mackie, and H. Shen, “Integrated ZnO nanotips on GaN light emitting diodes for enhanced emission efficiency,” Appl. Phys. Lett. 90(20), 203515 (2007).
[CrossRef]

Chu, J. T.

H. W. Huang, J. T. Chu, C. C. Kao, T. H. Hseuh, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Enhanced light output of an InGaN/GaN light emitting diode with a nano-roughened p-GaN surface,” Nanotechnology 16(9), 1844–1848 (2005).
[CrossRef]

H. W. Huang, C. C. Kao, J. T. Chu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Improvement of InGaN–GaN light-emitting diode performance with a nano-roughened p-GaN surface,” IEEE Photon. Technol. Lett. 17(5), 983–985 (2005).
[CrossRef]

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

Crawford, M. H.

J. K. Kim, S. Chhajed, M. F. Schubert, E. F. Schubert, A. J. Fischer, M. H. Crawford, J. Cho, H. Kim, and C. Sone, “Light-Extraction Enhancement of GaInN Light-Emitting Diodes by Graded-Refractive-Index Indium Tin Oxide Anti-Reflection Contact,” Adv. Mater. 20(4), 801–804 (2008).
[CrossRef]

J. Han, M. H. Crawford, R. J. Shul, J. J. Figiel, M. Banas, L. Zhang, Y. K. Song, H. Zhou, and A. V. Nurmikko, “AlGaN/GaN quantum well ultraviolet light emitting diodes,” Appl. Phys. Lett. 73(12), 1688 (1998).
[CrossRef]

DenBaars, S. P.

T. Fujii, Y. Gao, R. Sharma, E. L. Hu, S. P. DenBaars, and S. Nakamura, “Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening,” Appl. Phys. Lett. 84(6), 855–857 (2004).
[CrossRef]

Eto, T.

H. Hashimoto, A. Kumao, T. Eto, and K. Fujiwara, “Drops of oxides on tungsten oxide needles and nuclei of dendritic crystals,” J. Cryst. Growth 7(1), 113–116 (1970).
[CrossRef]

H. Hashimoto, T. Naiki, T. Eto, and K. Fujiwara, “High Temperature Gas Reaction Specimen Chamber for an Electron Microscope,” J. Appl. Phys. 7(8), 946–952 (1968).
[CrossRef]

Figiel, J. J.

J. Han, M. H. Crawford, R. J. Shul, J. J. Figiel, M. Banas, L. Zhang, Y. K. Song, H. Zhou, and A. V. Nurmikko, “AlGaN/GaN quantum well ultraviolet light emitting diodes,” Appl. Phys. Lett. 73(12), 1688 (1998).
[CrossRef]

Fischer, A. J.

J. K. Kim, S. Chhajed, M. F. Schubert, E. F. Schubert, A. J. Fischer, M. H. Crawford, J. Cho, H. Kim, and C. Sone, “Light-Extraction Enhancement of GaInN Light-Emitting Diodes by Graded-Refractive-Index Indium Tin Oxide Anti-Reflection Contact,” Adv. Mater. 20(4), 801–804 (2008).
[CrossRef]

Fujii, T.

T. Fujii, Y. Gao, R. Sharma, E. L. Hu, S. P. DenBaars, and S. Nakamura, “Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening,” Appl. Phys. Lett. 84(6), 855–857 (2004).
[CrossRef]

Fujiwara, K.

H. Hashimoto, A. Kumao, T. Eto, and K. Fujiwara, “Drops of oxides on tungsten oxide needles and nuclei of dendritic crystals,” J. Cryst. Growth 7(1), 113–116 (1970).
[CrossRef]

H. Hashimoto, T. Naiki, T. Eto, and K. Fujiwara, “High Temperature Gas Reaction Specimen Chamber for an Electron Microscope,” J. Appl. Phys. 7(8), 946–952 (1968).
[CrossRef]

Gao, Y.

T. Fujii, Y. Gao, R. Sharma, E. L. Hu, S. P. DenBaars, and S. Nakamura, “Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening,” Appl. Phys. Lett. 84(6), 855–857 (2004).
[CrossRef]

Han, J.

J. Han, M. H. Crawford, R. J. Shul, J. J. Figiel, M. Banas, L. Zhang, Y. K. Song, H. Zhou, and A. V. Nurmikko, “AlGaN/GaN quantum well ultraviolet light emitting diodes,” Appl. Phys. Lett. 73(12), 1688 (1998).
[CrossRef]

Hashimoto, H.

H. Hashimoto, A. Kumao, T. Eto, and K. Fujiwara, “Drops of oxides on tungsten oxide needles and nuclei of dendritic crystals,” J. Cryst. Growth 7(1), 113–116 (1970).
[CrossRef]

H. Hashimoto, T. Naiki, T. Eto, and K. Fujiwara, “High Temperature Gas Reaction Specimen Chamber for an Electron Microscope,” J. Appl. Phys. 7(8), 946–952 (1968).
[CrossRef]

Horng, R. H.

R. H. Horng, S. H. Huang, C. C. Yang, and D. S. Wuu, “Efficiency Improvement of GaN-Based LEDs with ITO Texturing Window Layers Using Natural Lithography,” IEEE J. Sel. Top. Quantum Electron. 12(6), 1196–1201 (2006).
[CrossRef]

Hoshino, K.

F. Ishida, K. Yoshimura, K. Hoshino, and K. Tadatomo, “Improved light extraction efficiency of GaN-based light emitting diodes by using needle-shape indium tin oxide p-contact,” Phys. Status Solidi 5(6 c), 2083–2085 (2008).
[CrossRef]

Hseuh, T. H.

H. W. Huang, J. T. Chu, C. C. Kao, T. H. Hseuh, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Enhanced light output of an InGaN/GaN light emitting diode with a nano-roughened p-GaN surface,” Nanotechnology 16(9), 1844–1848 (2005).
[CrossRef]

Hsiao, C. S.

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

Hsieh, M. H.

Y. J. Lee, J. M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Photon. Technol. Lett. 18(10), 1152–1154 (2006).
[CrossRef]

Hsieh, Y. L.

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

Hsu, S. H.

P. Yu, C. H. Chang, C. H. Chiu, C. S. Yang, J. C. Yu, H. C. Kuo, S. H. Hsu, and Y. C. Chang, “Efficiency Enhancement of GaAs Photovoltaics Employing Anti-Reflective Indium-Tin-Oxide Nano-Columns,” Adv. Mater. 21(16), 1618–1621 (2009).
[CrossRef]

C. H. Chiu, P. Yu, H. C. Kuo, C. C. Chen, T. C. Lu, S. C. Wang, S. H. Hsu, Y. J. Cheng, and Y. C. Chang, “Broadband and omnidirectional antireflection employing disordered GaN nanopillars,” Opt. Express 16(12), 8748–8754 (2008).
[CrossRef] [PubMed]

Hsu, T. C.

Y. J. Lee, J. M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Photon. Technol. Lett. 18(10), 1152–1154 (2006).
[CrossRef]

Hu, E. L.

T. Fujii, Y. Gao, R. Sharma, E. L. Hu, S. P. DenBaars, and S. Nakamura, “Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening,” Appl. Phys. Lett. 84(6), 855–857 (2004).
[CrossRef]

Huang, H. W.

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

C. H. Chiu, H. C. Kuo, C. E. Lee, C. H. Lin, P. C. Cheng, H. W. Huang, T. C. Lu, S. C. Wang, and K. M. Leung, “Fabrication and characteristics of thin-film InGaN–GaN light-emitting diodes with TiO2/SiO2 omnidirectional reflectors,” Semicond. Sci. Technol. 22(7), 831–835 (2007).
[CrossRef]

H. W. Huang, J. T. Chu, C. C. Kao, T. H. Hseuh, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Enhanced light output of an InGaN/GaN light emitting diode with a nano-roughened p-GaN surface,” Nanotechnology 16(9), 1844–1848 (2005).
[CrossRef]

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

H. W. Huang, C. C. Kao, J. T. Chu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Improvement of InGaN–GaN light-emitting diode performance with a nano-roughened p-GaN surface,” IEEE Photon. Technol. Lett. 17(5), 983–985 (2005).
[CrossRef]

Huang, S. H.

R. H. Horng, S. H. Huang, C. C. Yang, and D. S. Wuu, “Efficiency Improvement of GaN-Based LEDs with ITO Texturing Window Layers Using Natural Lithography,” IEEE J. Sel. Top. Quantum Electron. 12(6), 1196–1201 (2006).
[CrossRef]

Hwang, J. M.

Y. J. Lee, J. M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Photon. Technol. Lett. 18(10), 1152–1154 (2006).
[CrossRef]

Ishida, F.

F. Ishida, K. Yoshimura, K. Hoshino, and K. Tadatomo, “Improved light extraction efficiency of GaN-based light emitting diodes by using needle-shape indium tin oxide p-contact,” Phys. Status Solidi 5(6 c), 2083–2085 (2008).
[CrossRef]

Izuno, K.

Y. Narukawa, I. Niki, K. Izuno, M. Yamada, Y. Murazaki, and T. Mukai, “Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip,” J. Appl. Phys. 41(Part 2, No. 4A), L371–L373 (2002).

Jou, M. J.

Y. J. Lee, J. M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Photon. Technol. Lett. 18(10), 1152–1154 (2006).
[CrossRef]

Kao, C. C.

H. W. Huang, C. C. Kao, J. T. Chu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Improvement of InGaN–GaN light-emitting diode performance with a nano-roughened p-GaN surface,” IEEE Photon. Technol. Lett. 17(5), 983–985 (2005).
[CrossRef]

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

H. W. Huang, J. T. Chu, C. C. Kao, T. H. Hseuh, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Enhanced light output of an InGaN/GaN light emitting diode with a nano-roughened p-GaN surface,” Nanotechnology 16(9), 1844–1848 (2005).
[CrossRef]

Kim, D. W.

D. W. Kim, H. Y. Lee, M. C. Yoo, and G. Y. Yeom, “Highly efficient vertical laser-liftoff GaN-based light-emitting diodes formed by optimization of the cathode structure,” Appl. Phys. Lett. 86(5), 052108 (2005).
[CrossRef]

Kim, H.

J. K. Kim, S. Chhajed, M. F. Schubert, E. F. Schubert, A. J. Fischer, M. H. Crawford, J. Cho, H. Kim, and C. Sone, “Light-Extraction Enhancement of GaInN Light-Emitting Diodes by Graded-Refractive-Index Indium Tin Oxide Anti-Reflection Contact,” Adv. Mater. 20(4), 801–804 (2008).
[CrossRef]

Kim, J. K.

J. K. Kim, S. Chhajed, M. F. Schubert, E. F. Schubert, A. J. Fischer, M. H. Crawford, J. Cho, H. Kim, and C. Sone, “Light-Extraction Enhancement of GaInN Light-Emitting Diodes by Graded-Refractive-Index Indium Tin Oxide Anti-Reflection Contact,” Adv. Mater. 20(4), 801–804 (2008).
[CrossRef]

Kim, Y. C.

J. H. Lee, J. T. Oh, Y. C. Kim, and J. H. Lee, “Stress Reduction and Enhanced Extraction Efficiency of GaN-Based LED Grown on Cone-Shape-Patterned Sapphire,” IEEE Photon. Technol. Lett. 20(18), 1563–1565 (2008).
[CrossRef]

Kumao, A.

H. Hashimoto, A. Kumao, T. Eto, and K. Fujiwara, “Drops of oxides on tungsten oxide needles and nuclei of dendritic crystals,” J. Cryst. Growth 7(1), 113–116 (1970).
[CrossRef]

Kuo, H. C.

P. Yu, C. H. Chang, C. H. Chiu, C. S. Yang, J. C. Yu, H. C. Kuo, S. H. Hsu, and Y. C. Chang, “Efficiency Enhancement of GaAs Photovoltaics Employing Anti-Reflective Indium-Tin-Oxide Nano-Columns,” Adv. Mater. 21(16), 1618–1621 (2009).
[CrossRef]

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

C. H. Chiu, P. Yu, H. C. Kuo, C. C. Chen, T. C. Lu, S. C. Wang, S. H. Hsu, Y. J. Cheng, and Y. C. Chang, “Broadband and omnidirectional antireflection employing disordered GaN nanopillars,” Opt. Express 16(12), 8748–8754 (2008).
[CrossRef] [PubMed]

C. H. Chiu, H. C. Kuo, C. E. Lee, C. H. Lin, P. C. Cheng, H. W. Huang, T. C. Lu, S. C. Wang, and K. M. Leung, “Fabrication and characteristics of thin-film InGaN–GaN light-emitting diodes with TiO2/SiO2 omnidirectional reflectors,” Semicond. Sci. Technol. 22(7), 831–835 (2007).
[CrossRef]

Y. J. Lee, J. M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Photon. Technol. Lett. 18(10), 1152–1154 (2006).
[CrossRef]

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

H. W. Huang, C. C. Kao, J. T. Chu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Improvement of InGaN–GaN light-emitting diode performance with a nano-roughened p-GaN surface,” IEEE Photon. Technol. Lett. 17(5), 983–985 (2005).
[CrossRef]

H. W. Huang, J. T. Chu, C. C. Kao, T. H. Hseuh, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Enhanced light output of an InGaN/GaN light emitting diode with a nano-roughened p-GaN surface,” Nanotechnology 16(9), 1844–1848 (2005).
[CrossRef]

Kuo, W. L.

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

Lee, B. J.

Y. J. Lee, J. M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Photon. Technol. Lett. 18(10), 1152–1154 (2006).
[CrossRef]

Lee, C. E.

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

C. H. Chiu, H. C. Kuo, C. E. Lee, C. H. Lin, P. C. Cheng, H. W. Huang, T. C. Lu, S. C. Wang, and K. M. Leung, “Fabrication and characteristics of thin-film InGaN–GaN light-emitting diodes with TiO2/SiO2 omnidirectional reflectors,” Semicond. Sci. Technol. 22(7), 831–835 (2007).
[CrossRef]

Lee, H. Y.

D. W. Kim, H. Y. Lee, M. C. Yoo, and G. Y. Yeom, “Highly efficient vertical laser-liftoff GaN-based light-emitting diodes formed by optimization of the cathode structure,” Appl. Phys. Lett. 86(5), 052108 (2005).
[CrossRef]

Lee, J. H.

J. H. Lee, J. T. Oh, Y. C. Kim, and J. H. Lee, “Stress Reduction and Enhanced Extraction Efficiency of GaN-Based LED Grown on Cone-Shape-Patterned Sapphire,” IEEE Photon. Technol. Lett. 20(18), 1563–1565 (2008).
[CrossRef]

J. H. Lee, J. T. Oh, Y. C. Kim, and J. H. Lee, “Stress Reduction and Enhanced Extraction Efficiency of GaN-Based LED Grown on Cone-Shape-Patterned Sapphire,” IEEE Photon. Technol. Lett. 20(18), 1563–1565 (2008).
[CrossRef]

Lee, Y. J.

Y. J. Lee, J. M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Photon. Technol. Lett. 18(10), 1152–1154 (2006).
[CrossRef]

Leung, K. M.

C. H. Chiu, H. C. Kuo, C. E. Lee, C. H. Lin, P. C. Cheng, H. W. Huang, T. C. Lu, S. C. Wang, and K. M. Leung, “Fabrication and characteristics of thin-film InGaN–GaN light-emitting diodes with TiO2/SiO2 omnidirectional reflectors,” Semicond. Sci. Technol. 22(7), 831–835 (2007).
[CrossRef]

Lin, C. F.

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

Lin, C. H.

C. H. Chiu, H. C. Kuo, C. E. Lee, C. H. Lin, P. C. Cheng, H. W. Huang, T. C. Lu, S. C. Wang, and K. M. Leung, “Fabrication and characteristics of thin-film InGaN–GaN light-emitting diodes with TiO2/SiO2 omnidirectional reflectors,” Semicond. Sci. Technol. 22(7), 831–835 (2007).
[CrossRef]

Lu, T. C.

C. H. Chiu, P. Yu, H. C. Kuo, C. C. Chen, T. C. Lu, S. C. Wang, S. H. Hsu, Y. J. Cheng, and Y. C. Chang, “Broadband and omnidirectional antireflection employing disordered GaN nanopillars,” Opt. Express 16(12), 8748–8754 (2008).
[CrossRef] [PubMed]

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

C. H. Chiu, H. C. Kuo, C. E. Lee, C. H. Lin, P. C. Cheng, H. W. Huang, T. C. Lu, S. C. Wang, and K. M. Leung, “Fabrication and characteristics of thin-film InGaN–GaN light-emitting diodes with TiO2/SiO2 omnidirectional reflectors,” Semicond. Sci. Technol. 22(7), 831–835 (2007).
[CrossRef]

Y. J. Lee, J. M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Photon. Technol. Lett. 18(10), 1152–1154 (2006).
[CrossRef]

H. W. Huang, J. T. Chu, C. C. Kao, T. H. Hseuh, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Enhanced light output of an InGaN/GaN light emitting diode with a nano-roughened p-GaN surface,” Nanotechnology 16(9), 1844–1848 (2005).
[CrossRef]

Lu, Y.

J. Zhong, H. Chen, G. Saraf, Y. Lu, C. K. Choi, J. J. Song, D. M. Mackie, and H. Shen, “Integrated ZnO nanotips on GaN light emitting diodes for enhanced emission efficiency,” Appl. Phys. Lett. 90(20), 203515 (2007).
[CrossRef]

Luo, C. Y.

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

Mackie, D. M.

J. Zhong, H. Chen, G. Saraf, Y. Lu, C. K. Choi, J. J. Song, D. M. Mackie, and H. Shen, “Integrated ZnO nanotips on GaN light emitting diodes for enhanced emission efficiency,” Appl. Phys. Lett. 90(20), 203515 (2007).
[CrossRef]

Mukai, T.

Y. Narukawa, I. Niki, K. Izuno, M. Yamada, Y. Murazaki, and T. Mukai, “Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip,” J. Appl. Phys. 41(Part 2, No. 4A), L371–L373 (2002).

Murazaki, Y.

Y. Narukawa, I. Niki, K. Izuno, M. Yamada, Y. Murazaki, and T. Mukai, “Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip,” J. Appl. Phys. 41(Part 2, No. 4A), L371–L373 (2002).

Naiki, T.

H. Hashimoto, T. Naiki, T. Eto, and K. Fujiwara, “High Temperature Gas Reaction Specimen Chamber for an Electron Microscope,” J. Appl. Phys. 7(8), 946–952 (1968).
[CrossRef]

Nakamura, S.

T. Fujii, Y. Gao, R. Sharma, E. L. Hu, S. P. DenBaars, and S. Nakamura, “Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening,” Appl. Phys. Lett. 84(6), 855–857 (2004).
[CrossRef]

Narukawa, Y.

Y. Narukawa, I. Niki, K. Izuno, M. Yamada, Y. Murazaki, and T. Mukai, “Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip,” J. Appl. Phys. 41(Part 2, No. 4A), L371–L373 (2002).

Niki, I.

Y. Narukawa, I. Niki, K. Izuno, M. Yamada, Y. Murazaki, and T. Mukai, “Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip,” J. Appl. Phys. 41(Part 2, No. 4A), L371–L373 (2002).

Nurmikko, A. V.

J. Han, M. H. Crawford, R. J. Shul, J. J. Figiel, M. Banas, L. Zhang, Y. K. Song, H. Zhou, and A. V. Nurmikko, “AlGaN/GaN quantum well ultraviolet light emitting diodes,” Appl. Phys. Lett. 73(12), 1688 (1998).
[CrossRef]

Oh, J. T.

J. H. Lee, J. T. Oh, Y. C. Kim, and J. H. Lee, “Stress Reduction and Enhanced Extraction Efficiency of GaN-Based LED Grown on Cone-Shape-Patterned Sapphire,” IEEE Photon. Technol. Lett. 20(18), 1563–1565 (2008).
[CrossRef]

Peng, Y. C.

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

Saraf, G.

J. Zhong, H. Chen, G. Saraf, Y. Lu, C. K. Choi, J. J. Song, D. M. Mackie, and H. Shen, “Integrated ZnO nanotips on GaN light emitting diodes for enhanced emission efficiency,” Appl. Phys. Lett. 90(20), 203515 (2007).
[CrossRef]

Satoh, R.

S. Takaki, Y. Aoshima, and R. Satoh, “Growth Mechanism of Indium Tin Oxide Whiskers Prepared by Sputtering,” J. Appl. Phys. 46(No. 6A), 3537–3544 (2007).
[CrossRef]

Schubert, E. F.

J. K. Kim, S. Chhajed, M. F. Schubert, E. F. Schubert, A. J. Fischer, M. H. Crawford, J. Cho, H. Kim, and C. Sone, “Light-Extraction Enhancement of GaInN Light-Emitting Diodes by Graded-Refractive-Index Indium Tin Oxide Anti-Reflection Contact,” Adv. Mater. 20(4), 801–804 (2008).
[CrossRef]

Schubert, M. F.

J. K. Kim, S. Chhajed, M. F. Schubert, E. F. Schubert, A. J. Fischer, M. H. Crawford, J. Cho, H. Kim, and C. Sone, “Light-Extraction Enhancement of GaInN Light-Emitting Diodes by Graded-Refractive-Index Indium Tin Oxide Anti-Reflection Contact,” Adv. Mater. 20(4), 801–804 (2008).
[CrossRef]

Sharma, R.

T. Fujii, Y. Gao, R. Sharma, E. L. Hu, S. P. DenBaars, and S. Nakamura, “Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening,” Appl. Phys. Lett. 84(6), 855–857 (2004).
[CrossRef]

Shen, H.

J. Zhong, H. Chen, G. Saraf, Y. Lu, C. K. Choi, J. J. Song, D. M. Mackie, and H. Shen, “Integrated ZnO nanotips on GaN light emitting diodes for enhanced emission efficiency,” Appl. Phys. Lett. 90(20), 203515 (2007).
[CrossRef]

Shul, R. J.

J. Han, M. H. Crawford, R. J. Shul, J. J. Figiel, M. Banas, L. Zhang, Y. K. Song, H. Zhou, and A. V. Nurmikko, “AlGaN/GaN quantum well ultraviolet light emitting diodes,” Appl. Phys. Lett. 73(12), 1688 (1998).
[CrossRef]

Sone, C.

J. K. Kim, S. Chhajed, M. F. Schubert, E. F. Schubert, A. J. Fischer, M. H. Crawford, J. Cho, H. Kim, and C. Sone, “Light-Extraction Enhancement of GaInN Light-Emitting Diodes by Graded-Refractive-Index Indium Tin Oxide Anti-Reflection Contact,” Adv. Mater. 20(4), 801–804 (2008).
[CrossRef]

Song, J. J.

J. Zhong, H. Chen, G. Saraf, Y. Lu, C. K. Choi, J. J. Song, D. M. Mackie, and H. Shen, “Integrated ZnO nanotips on GaN light emitting diodes for enhanced emission efficiency,” Appl. Phys. Lett. 90(20), 203515 (2007).
[CrossRef]

Song, Y. K.

J. Han, M. H. Crawford, R. J. Shul, J. J. Figiel, M. Banas, L. Zhang, Y. K. Song, H. Zhou, and A. V. Nurmikko, “AlGaN/GaN quantum well ultraviolet light emitting diodes,” Appl. Phys. Lett. 73(12), 1688 (1998).
[CrossRef]

Tadatomo, K.

F. Ishida, K. Yoshimura, K. Hoshino, and K. Tadatomo, “Improved light extraction efficiency of GaN-based light emitting diodes by using needle-shape indium tin oxide p-contact,” Phys. Status Solidi 5(6 c), 2083–2085 (2008).
[CrossRef]

Takaki, S.

S. Takaki, Y. Aoshima, and R. Satoh, “Growth Mechanism of Indium Tin Oxide Whiskers Prepared by Sputtering,” J. Appl. Phys. 46(No. 6A), 3537–3544 (2007).
[CrossRef]

Wang, S. C.

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

C. H. Chiu, P. Yu, H. C. Kuo, C. C. Chen, T. C. Lu, S. C. Wang, S. H. Hsu, Y. J. Cheng, and Y. C. Chang, “Broadband and omnidirectional antireflection employing disordered GaN nanopillars,” Opt. Express 16(12), 8748–8754 (2008).
[CrossRef] [PubMed]

C. H. Chiu, H. C. Kuo, C. E. Lee, C. H. Lin, P. C. Cheng, H. W. Huang, T. C. Lu, S. C. Wang, and K. M. Leung, “Fabrication and characteristics of thin-film InGaN–GaN light-emitting diodes with TiO2/SiO2 omnidirectional reflectors,” Semicond. Sci. Technol. 22(7), 831–835 (2007).
[CrossRef]

Y. J. Lee, J. M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Photon. Technol. Lett. 18(10), 1152–1154 (2006).
[CrossRef]

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

H. W. Huang, C. C. Kao, J. T. Chu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Improvement of InGaN–GaN light-emitting diode performance with a nano-roughened p-GaN surface,” IEEE Photon. Technol. Lett. 17(5), 983–985 (2005).
[CrossRef]

H. W. Huang, J. T. Chu, C. C. Kao, T. H. Hseuh, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Enhanced light output of an InGaN/GaN light emitting diode with a nano-roughened p-GaN surface,” Nanotechnology 16(9), 1844–1848 (2005).
[CrossRef]

Wuu, D. S.

R. H. Horng, S. H. Huang, C. C. Yang, and D. S. Wuu, “Efficiency Improvement of GaN-Based LEDs with ITO Texturing Window Layers Using Natural Lithography,” IEEE J. Sel. Top. Quantum Electron. 12(6), 1196–1201 (2006).
[CrossRef]

Yamada, M.

Y. Narukawa, I. Niki, K. Izuno, M. Yamada, Y. Murazaki, and T. Mukai, “Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip,” J. Appl. Phys. 41(Part 2, No. 4A), L371–L373 (2002).

Yang, C. C.

R. H. Horng, S. H. Huang, C. C. Yang, and D. S. Wuu, “Efficiency Improvement of GaN-Based LEDs with ITO Texturing Window Layers Using Natural Lithography,” IEEE J. Sel. Top. Quantum Electron. 12(6), 1196–1201 (2006).
[CrossRef]

Yang, C. S.

P. Yu, C. H. Chang, C. H. Chiu, C. S. Yang, J. C. Yu, H. C. Kuo, S. H. Hsu, and Y. C. Chang, “Efficiency Enhancement of GaAs Photovoltaics Employing Anti-Reflective Indium-Tin-Oxide Nano-Columns,” Adv. Mater. 21(16), 1618–1621 (2009).
[CrossRef]

Yeom, G. Y.

D. W. Kim, H. Y. Lee, M. C. Yoo, and G. Y. Yeom, “Highly efficient vertical laser-liftoff GaN-based light-emitting diodes formed by optimization of the cathode structure,” Appl. Phys. Lett. 86(5), 052108 (2005).
[CrossRef]

Yoo, M. C.

D. W. Kim, H. Y. Lee, M. C. Yoo, and G. Y. Yeom, “Highly efficient vertical laser-liftoff GaN-based light-emitting diodes formed by optimization of the cathode structure,” Appl. Phys. Lett. 86(5), 052108 (2005).
[CrossRef]

Yoshimura, K.

F. Ishida, K. Yoshimura, K. Hoshino, and K. Tadatomo, “Improved light extraction efficiency of GaN-based light emitting diodes by using needle-shape indium tin oxide p-contact,” Phys. Status Solidi 5(6 c), 2083–2085 (2008).
[CrossRef]

Yu, C. C.

H. W. Huang, C. C. Kao, J. T. Chu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Improvement of InGaN–GaN light-emitting diode performance with a nano-roughened p-GaN surface,” IEEE Photon. Technol. Lett. 17(5), 983–985 (2005).
[CrossRef]

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

H. W. Huang, J. T. Chu, C. C. Kao, T. H. Hseuh, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Enhanced light output of an InGaN/GaN light emitting diode with a nano-roughened p-GaN surface,” Nanotechnology 16(9), 1844–1848 (2005).
[CrossRef]

Yu, J. C.

P. Yu, C. H. Chang, C. H. Chiu, C. S. Yang, J. C. Yu, H. C. Kuo, S. H. Hsu, and Y. C. Chang, “Efficiency Enhancement of GaAs Photovoltaics Employing Anti-Reflective Indium-Tin-Oxide Nano-Columns,” Adv. Mater. 21(16), 1618–1621 (2009).
[CrossRef]

Yu, P.

P. Yu, C. H. Chang, C. H. Chiu, C. S. Yang, J. C. Yu, H. C. Kuo, S. H. Hsu, and Y. C. Chang, “Efficiency Enhancement of GaAs Photovoltaics Employing Anti-Reflective Indium-Tin-Oxide Nano-Columns,” Adv. Mater. 21(16), 1618–1621 (2009).
[CrossRef]

C. H. Chiu, P. Yu, H. C. Kuo, C. C. Chen, T. C. Lu, S. C. Wang, S. H. Hsu, Y. J. Cheng, and Y. C. Chang, “Broadband and omnidirectional antireflection employing disordered GaN nanopillars,” Opt. Express 16(12), 8748–8754 (2008).
[CrossRef] [PubMed]

Zhang, L.

J. Han, M. H. Crawford, R. J. Shul, J. J. Figiel, M. Banas, L. Zhang, Y. K. Song, H. Zhou, and A. V. Nurmikko, “AlGaN/GaN quantum well ultraviolet light emitting diodes,” Appl. Phys. Lett. 73(12), 1688 (1998).
[CrossRef]

Zhong, J.

J. Zhong, H. Chen, G. Saraf, Y. Lu, C. K. Choi, J. J. Song, D. M. Mackie, and H. Shen, “Integrated ZnO nanotips on GaN light emitting diodes for enhanced emission efficiency,” Appl. Phys. Lett. 90(20), 203515 (2007).
[CrossRef]

Zhou, H.

J. Han, M. H. Crawford, R. J. Shul, J. J. Figiel, M. Banas, L. Zhang, Y. K. Song, H. Zhou, and A. V. Nurmikko, “AlGaN/GaN quantum well ultraviolet light emitting diodes,” Appl. Phys. Lett. 73(12), 1688 (1998).
[CrossRef]

. Appl. Phys. (1)

Y. Narukawa, I. Niki, K. Izuno, M. Yamada, Y. Murazaki, and T. Mukai, “Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip,” J. Appl. Phys. 41(Part 2, No. 4A), L371–L373 (2002).

Adv. Mater. (2)

J. K. Kim, S. Chhajed, M. F. Schubert, E. F. Schubert, A. J. Fischer, M. H. Crawford, J. Cho, H. Kim, and C. Sone, “Light-Extraction Enhancement of GaInN Light-Emitting Diodes by Graded-Refractive-Index Indium Tin Oxide Anti-Reflection Contact,” Adv. Mater. 20(4), 801–804 (2008).
[CrossRef]

P. Yu, C. H. Chang, C. H. Chiu, C. S. Yang, J. C. Yu, H. C. Kuo, S. H. Hsu, and Y. C. Chang, “Efficiency Enhancement of GaAs Photovoltaics Employing Anti-Reflective Indium-Tin-Oxide Nano-Columns,” Adv. Mater. 21(16), 1618–1621 (2009).
[CrossRef]

Appl. Phys. Lett. (4)

J. Han, M. H. Crawford, R. J. Shul, J. J. Figiel, M. Banas, L. Zhang, Y. K. Song, H. Zhou, and A. V. Nurmikko, “AlGaN/GaN quantum well ultraviolet light emitting diodes,” Appl. Phys. Lett. 73(12), 1688 (1998).
[CrossRef]

J. Zhong, H. Chen, G. Saraf, Y. Lu, C. K. Choi, J. J. Song, D. M. Mackie, and H. Shen, “Integrated ZnO nanotips on GaN light emitting diodes for enhanced emission efficiency,” Appl. Phys. Lett. 90(20), 203515 (2007).
[CrossRef]

T. Fujii, Y. Gao, R. Sharma, E. L. Hu, S. P. DenBaars, and S. Nakamura, “Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening,” Appl. Phys. Lett. 84(6), 855–857 (2004).
[CrossRef]

D. W. Kim, H. Y. Lee, M. C. Yoo, and G. Y. Yeom, “Highly efficient vertical laser-liftoff GaN-based light-emitting diodes formed by optimization of the cathode structure,” Appl. Phys. Lett. 86(5), 052108 (2005).
[CrossRef]

Elec. Sol. Sta. Lett. (1)

C. H. Chiu, C. E. Lee, C. L. Chao, B. S. Cheng, H. W. Huang, H. C. Kuo, T. C. Lu, S. C. Wang, W. L. Kuo, C. S. Hsiao, and S. Y. Chen, “Enhancement of Light Output Intensity by Integrating ZnO Nanorod Arrays on GaN-Based LLO Vertical LEDs,” Elec. Sol. Sta. Lett. 11(4), H84–H87 (2008).
[CrossRef]

IEEE J. Sel. Top. Quantum Electron. (1)

R. H. Horng, S. H. Huang, C. C. Yang, and D. S. Wuu, “Efficiency Improvement of GaN-Based LEDs with ITO Texturing Window Layers Using Natural Lithography,” IEEE J. Sel. Top. Quantum Electron. 12(6), 1196–1201 (2006).
[CrossRef]

IEEE Photon. Technol. Lett. (4)

H. W. Huang, C. C. Kao, J. T. Chu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Improvement of InGaN–GaN light-emitting diode performance with a nano-roughened p-GaN surface,” IEEE Photon. Technol. Lett. 17(5), 983–985 (2005).
[CrossRef]

C. C. Kao, H. C. Kuo, H. W. Huang, J. T. Chu, Y. C. Peng, Y. L. Hsieh, C. Y. Luo, S. C. Wang, C. C. Yu, and C. F. Lin, “Light-output enhancement in a nitride-based light-emitting diode with 22 undercut sidewalls,” IEEE Photon. Technol. Lett. 17(1), 19–21 (2005).
[CrossRef]

Y. J. Lee, J. M. Hwang, T. C. Hsu, M. H. Hsieh, M. J. Jou, B. J. Lee, T. C. Lu, H. C. Kuo, and S. C. Wang, “Enhancing the Output Power of GaN-Based LEDs Grown on Wet-Etched Patterned Sapphire Substrates,” IEEE Photon. Technol. Lett. 18(10), 1152–1154 (2006).
[CrossRef]

J. H. Lee, J. T. Oh, Y. C. Kim, and J. H. Lee, “Stress Reduction and Enhanced Extraction Efficiency of GaN-Based LED Grown on Cone-Shape-Patterned Sapphire,” IEEE Photon. Technol. Lett. 20(18), 1563–1565 (2008).
[CrossRef]

J. Appl. Phys. (2)

S. Takaki, Y. Aoshima, and R. Satoh, “Growth Mechanism of Indium Tin Oxide Whiskers Prepared by Sputtering,” J. Appl. Phys. 46(No. 6A), 3537–3544 (2007).
[CrossRef]

H. Hashimoto, T. Naiki, T. Eto, and K. Fujiwara, “High Temperature Gas Reaction Specimen Chamber for an Electron Microscope,” J. Appl. Phys. 7(8), 946–952 (1968).
[CrossRef]

J. Cryst. Growth (1)

H. Hashimoto, A. Kumao, T. Eto, and K. Fujiwara, “Drops of oxides on tungsten oxide needles and nuclei of dendritic crystals,” J. Cryst. Growth 7(1), 113–116 (1970).
[CrossRef]

Nanotechnology (1)

H. W. Huang, J. T. Chu, C. C. Kao, T. H. Hseuh, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Enhanced light output of an InGaN/GaN light emitting diode with a nano-roughened p-GaN surface,” Nanotechnology 16(9), 1844–1848 (2005).
[CrossRef]

Opt. Express (1)

Phys. Status Solidi (1)

F. Ishida, K. Yoshimura, K. Hoshino, and K. Tadatomo, “Improved light extraction efficiency of GaN-based light emitting diodes by using needle-shape indium tin oxide p-contact,” Phys. Status Solidi 5(6 c), 2083–2085 (2008).
[CrossRef]

Semicond. Sci. Technol. (1)

C. H. Chiu, H. C. Kuo, C. E. Lee, C. H. Lin, P. C. Cheng, H. W. Huang, T. C. Lu, S. C. Wang, and K. M. Leung, “Fabrication and characteristics of thin-film InGaN–GaN light-emitting diodes with TiO2/SiO2 omnidirectional reflectors,” Semicond. Sci. Technol. 22(7), 831–835 (2007).
[CrossRef]

Other (3)

D. Eisert and V. Harle, “Simulations in the development process of GaN based LEDs and laser diodes,” in Int. Conf. Numerical Simulation of Semiconductor Optoelectronic Devices, Session 3: Photonic Devices, invited paper (2002).

S. Nakamura, and G. Fasol, The Blue Laser Diode, (Springer, New York, 1997).

FullWAVE, Rsoft Design Group, Inc.

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Figures (7)

Fig. 1
Fig. 1

(a) Scanning electron micrograph of the nucleation cores at the beginning of evaporation, (b) the cross-sectional view of deposited nanorods, (c) the tunneling electron micrograph (TEM) of a nanorod, and (d) schematics for the ITO nanorod growth mechanism.

Fig. 2
Fig. 2

(a) Schematic diagram of fabricated LEDs with ITO nanorods on the surface and (b) the typical emission spectrum with normalized intensity.

Fig. 3
Fig. 3

The normalized transmittance for three samples containing a 240-nm-thick ITO thin film, ITO nanorods grown on the 240-nm-thick ITO thin film, and ITO nanorods only, prepared on fused silica substrates for the wavelength range of 350 to 900 nm.

Fig. 4
Fig. 4

The current-voltage (I-V) and electroluminescence (EL) characteristics of packaged LEDs with and without ITO nanorods. The inset shows the far-field radiation profile of both devices.

Fig. 5
Fig. 5

The spatial intensity distribution of LEDs (a) with and (b) without ITO nanorods at an injected current of 200 mA.

Fig. 6
Fig. 6

The calculated enhancement factor versus the thickness of the ITO nanorod layer using a three-dimension finite difference time domain (3D-FDTD) method. The inset shows the modeled index profile.

Fig. 7
Fig. 7

Lifetime test of LEDs with and without ITO nanorods over 1000 hours under an injection current of 350 mA.

Tables (1)

Tables Icon

Table 1 Defined structural parameters for 21x21 randomly oriented and positioned nanorods.

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