GaN-based light-emitting diodes with hybrid micro/nano-textured indium-tin-oxide layer

Huamao Huang; Jinyong Hu; Hong Wang

doi:10.1088/1674-4926/35/8/084006

J. Semicond. > 2014, Volume 35 > Issue 8 > 084006, doi: 10.1088/1674-4926/35/8/084006

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GaN-based light-emitting diodes with hybrid micro/nano-textured indium-tin-oxide layer

Huamao Huang, Jinyong Hu and Hong Wang

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Corresponding author: Wang Hong, Email:phhwang@scut.edu.cn

Abstract: Three types of textured indium-tin-oxide (ITO) surface, including nano-texturing and hybrid micro/nano-texturing with micro-holes (concave-hybrid-pattern) or micro-pillars (convex-hybrid-pattern), were applied to GaN-based light-emitting diodes (LEDs). The nano-texturing was realized by maskless wet-etching, and the micro-texturing was achieved by standard photolithography and wet-etching. Compared to LED chips with flat ITO surface, those with nano-pattern, concave-hybrid-pattern, and convex-hybrid-pattern exhibit enhancement of 11.3%, 15.8%, and 17.9%, respectively, for the light-output powers at 20 mA. The electrical performance has no degradation. Moreover, the convex-hybrid-pattern show higher light-output efficiency under small injection current, while the concave-hybrid-pattern exhibit better light-output efficiency at large injection current. The light-extraction efficiency is simulated by use of two-dimensional finite difference time domain method, and the numerical results are consistent with the experiments.

Key words: light-emitting diodes, hybrid micro/nano-textured, indium-tin-oxide, light-output

References

[1]	Zhmakin A I. Enhancement of light extraction from light emitting diodes. Phys Rep, 2011, 498:189 doi: 10.1016/j.physrep.2010.11.001
[2]	Pan S M, Tu R C, Fan Y M, et al. Improvement of InGaN-GaN light-emitting diodes with surface-textured indium-tin-oxide transparent ohmic contacts. IEEE Photon Tech Lett, 2003, 15(5):649 doi: 10.1109/LPT.2003.809985
[3]	Wang P, Cao B, Wei W, et al. Improved light extraction of GaN-based light-emitting diodes by ITO patterning with optimization design. Solid-State Electron, 2010, 54:283 doi: 10.1016/j.sse.2009.10.005
[4]	Tsai C F, Su Y K, Lin C L. Improvement in external quantum efficiency of InGaN-based LEDs by micro-textured surface with different geometric patterns. J Electrochem Soc, 2012, 159(2):H151 doi: 10.1149/2.055202jes
[5]	Chang S J, Shen C F, Chen W S, et al. Nitride-based light emitting diodes with indium tin oxide electrode patterned by imprint lithography. Appl Phys Lett, 2007, 91:013504 doi: 10.1063/1.2753726
[6]	Leem D S, Cho J, Sone C, et al. Light-output enhancement of GaN-based light-emitting diodes by using hole-patterned transparent indium tin oxide electrodes. J Appl Phys, 2005, 98:076107. doi: 10.1063/1.2081117
[7]	Horng R H, Yang C C, Wu J Y, et al. GaN-based light-emitting diodes with indium tin oxide texturing window layers using natural lithography. Appl Phys Lett, 2005, 86:221101 doi: 10.1063/1.1940723
[8]	He Anhe, Zhang Yong, Zhu Xuehui, et al. Improved light extraction of GaN-based light-emitting diodes with surface-textured indium tin oxide electrodes by nickel nanoparticle mask dry-etching. Chin Phys B, 2010, 19(6):068101 doi: 10.1088/1674-1056/19/6/068101
[9]	Liao C, Wu Y S. InGaN-GaN light emitting diode performance improved by roughening indium tin oxide window layer via natural lithography. Electrochem Solid State Lett, 2010, 13(1):J8 doi: 10.1149/1.3257601
[10]	Leem D S, Lee T, Seong T Y. Enhancement of the light output of GaN-based light-emitting diodes with surface-patterned ITO electrodes by maskless wet-etching. Solid-State Electron, 2007, 51:793 doi: 10.1016/j.sse.2007.02.038
[11]	Kang J H, Kim H G, Ryu J H, et al. Enhancement of light output power in InGaN/GaN LEDs with nanoroughed hemispherical indium tin oxide transparent ohmic contacts. Electrochem Solid State Lett, 2010, 13(2):D1 doi: 10.1149/1.3261741
[12]	Kang J H, Ryu J H, Kim H K, et al. Comparison of various surface textured layer in InGaN LEDs for high light extraction efficiency. Opt Express, 2011, 19(4):3637 doi: 10.1364/OE.19.003637
[13]	Kang J H, Kim H G, Kim H K, et al. Improvement of light output power in InGaN/GaN light-emitting diodes with a nanotextured GaN surface using indium tin oxide nanospheres. Jpn J Appl Phys, 2009, 48:102104 doi: 10.1143/JJAP.48.102104
[14]	Li S, Kuo D S, Liu C H, et al. Efficiency improvement of GaN-based light-emitting diodes by direct wet etching of indium-tin-oxide layer. IET Optoelectron, 2012, 6(6):303 doi: 10.1049/iet-opt.2012.0019
[15]	Huh C, Lee J M, Kim D J, et al. Improvement in light-output efficiency of InGaN/GaN multiple-quantum well light-emitting diodes by current blocking layer. J Appl Phys, 2002, 92(5):2248 doi: 10.1063/1.1497467
[16]	Pan J W, Tsai P J, Chang K D, et al. Light extraction efficiency analysis of GaN-based light-emitting diodes with nanopatterned sapphire substrates. Appl Opt, 2013, 52(7):1358 doi: 10.1364/AO.52.001358

Fig. 1. Fabrication processes of LED chips with hybrid micro/nano-textured ITO surface. (a) Mesa etching, (b) CBL fabrication, (c) ITO deposition, (d) nano-texturing realized by maskless wet-eching, (e) standard photolithography for micro-texturing, (f) micro-texturing achieved by wet-etching with mask, (g) electrode fabrication, and (h) SiO$_{2}$ passivation.

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Fig. 2. SEM images of ITO surface in (a) flat samples, (b) nano-textured samples, (c) concave-hybrid-textured samples, and (d) convex-hybrid-textured samples.

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Fig. 3. The functional curves of forward voltage versus injection current.

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Fig. 4. The functional curves of light-output power versus injection current.

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Fig. 5. The functional curves of light-output efficiency versus injection current.

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Fig. 6. 2D-FDTD model for convex-hybrid-textured samples. The gray circles are the three typical locations for dipole source.

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[1]	Zhmakin A I. Enhancement of light extraction from light emitting diodes. Phys Rep, 2011, 498:189 doi: 10.1016/j.physrep.2010.11.001
[2]	Pan S M, Tu R C, Fan Y M, et al. Improvement of InGaN-GaN light-emitting diodes with surface-textured indium-tin-oxide transparent ohmic contacts. IEEE Photon Tech Lett, 2003, 15(5):649 doi: 10.1109/LPT.2003.809985
[3]	Wang P, Cao B, Wei W, et al. Improved light extraction of GaN-based light-emitting diodes by ITO patterning with optimization design. Solid-State Electron, 2010, 54:283 doi: 10.1016/j.sse.2009.10.005
[4]	Tsai C F, Su Y K, Lin C L. Improvement in external quantum efficiency of InGaN-based LEDs by micro-textured surface with different geometric patterns. J Electrochem Soc, 2012, 159(2):H151 doi: 10.1149/2.055202jes
[5]	Chang S J, Shen C F, Chen W S, et al. Nitride-based light emitting diodes with indium tin oxide electrode patterned by imprint lithography. Appl Phys Lett, 2007, 91:013504 doi: 10.1063/1.2753726
[6]	Leem D S, Cho J, Sone C, et al. Light-output enhancement of GaN-based light-emitting diodes by using hole-patterned transparent indium tin oxide electrodes. J Appl Phys, 2005, 98:076107. doi: 10.1063/1.2081117
[7]	Horng R H, Yang C C, Wu J Y, et al. GaN-based light-emitting diodes with indium tin oxide texturing window layers using natural lithography. Appl Phys Lett, 2005, 86:221101 doi: 10.1063/1.1940723
[8]	He Anhe, Zhang Yong, Zhu Xuehui, et al. Improved light extraction of GaN-based light-emitting diodes with surface-textured indium tin oxide electrodes by nickel nanoparticle mask dry-etching. Chin Phys B, 2010, 19(6):068101 doi: 10.1088/1674-1056/19/6/068101
[9]	Liao C, Wu Y S. InGaN-GaN light emitting diode performance improved by roughening indium tin oxide window layer via natural lithography. Electrochem Solid State Lett, 2010, 13(1):J8 doi: 10.1149/1.3257601
[10]	Leem D S, Lee T, Seong T Y. Enhancement of the light output of GaN-based light-emitting diodes with surface-patterned ITO electrodes by maskless wet-etching. Solid-State Electron, 2007, 51:793 doi: 10.1016/j.sse.2007.02.038
[11]	Kang J H, Kim H G, Ryu J H, et al. Enhancement of light output power in InGaN/GaN LEDs with nanoroughed hemispherical indium tin oxide transparent ohmic contacts. Electrochem Solid State Lett, 2010, 13(2):D1 doi: 10.1149/1.3261741
[12]	Kang J H, Ryu J H, Kim H K, et al. Comparison of various surface textured layer in InGaN LEDs for high light extraction efficiency. Opt Express, 2011, 19(4):3637 doi: 10.1364/OE.19.003637
[13]	Kang J H, Kim H G, Kim H K, et al. Improvement of light output power in InGaN/GaN light-emitting diodes with a nanotextured GaN surface using indium tin oxide nanospheres. Jpn J Appl Phys, 2009, 48:102104 doi: 10.1143/JJAP.48.102104
[14]	Li S, Kuo D S, Liu C H, et al. Efficiency improvement of GaN-based light-emitting diodes by direct wet etching of indium-tin-oxide layer. IET Optoelectron, 2012, 6(6):303 doi: 10.1049/iet-opt.2012.0019
[15]	Huh C, Lee J M, Kim D J, et al. Improvement in light-output efficiency of InGaN/GaN multiple-quantum well light-emitting diodes by current blocking layer. J Appl Phys, 2002, 92(5):2248 doi: 10.1063/1.1497467
[16]	Pan J W, Tsai P J, Chang K D, et al. Light extraction efficiency analysis of GaN-based light-emitting diodes with nanopatterned sapphire substrates. Appl Opt, 2013, 52(7):1358 doi: 10.1364/AO.52.001358

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Received: 19 February 2014 Revised: 04 April 2014 Online: Published: 01 August 2014

Article Navigation > Journal of Semiconductors > 2014 > 35(8): 084006

Huamao Huang, Jinyong Hu, Hong Wang. GaN-based light-emitting diodes with hybrid micro/nano-textured indium-tin-oxide layer[J]. Journal of Semiconductors, 2014, 35(8): 084006. doi: 10.1088/1674-4926/35/8/084006 H M Huang, J Y Hu, H Wang. GaN-based light-emitting diodes with hybrid micro/nano-textured indium-tin-oxide layer[J]. J. Semicond., 2014, 35(8): 084006. doi: 10.1088/1674-4926/35/8/084006.Export: BibTex EndNote

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Huamao Huang, Jinyong Hu, Hong Wang. GaN-based light-emitting diodes with hybrid micro/nano-textured indium-tin-oxide layer[J]. Journal of Semiconductors, 2014, 35(8): 084006. doi: 10.1088/1674-4926/35/8/084006

H M Huang, J Y Hu, H Wang. GaN-based light-emitting diodes with hybrid micro/nano-textured indium-tin-oxide layer[J]. J. Semicond., 2014, 35(8): 084006. doi: 10.1088/1674-4926/35/8/084006.

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H M Huang, J Y Hu, H Wang. GaN-based light-emitting diodes with hybrid micro/nano-textured indium-tin-oxide layer[J]. J. Semicond., 2014, 35(8): 084006. doi: 10.1088/1674-4926/35/8/084006.

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GaN-based light-emitting diodes with hybrid micro/nano-textured indium-tin-oxide layer

doi: 10.1088/1674-4926/35/8/084006

Engineering Research Center for Optoelectronics of Guangdong Province, Department of Physics, School of Science, South China University of Technology, Guangzhou 510640, China

Funds:

the Fundamental Research Funds for the Central Universities 2013ZM093

the Fundamental Research Funds for the Central Universities 2013ZP0017

the National High Technology Research and Development Program of China 2014AA032609

the Strategic Emerging Industry Special Funds of Guangdong Province 2010A081002009

the Strategic Emerging Industry Special Funds of Guangdong Province 2011A081301004

Project supported by the National High Technology Research and Development Program of China (No. 2014AA032609), the Strategic Emerging Industry Special Funds of Guangdong Province (Nos. 2010A081002009, 2011A081301004, 2012A080302003), and the Fundamental Research Funds for the Central Universities (Nos. 2013ZM093, 2013ZP0017)

the Strategic Emerging Industry Special Funds of Guangdong Province 2012A080302003

More Information

Corresponding author: Wang Hong, Email:phhwang@scut.edu.cn
Received Date: 2014-02-19
Revised Date: 2014-04-04
Published Date: 2014-08-01

Abstract

Abstract

Three types of textured indium-tin-oxide (ITO) surface, including nano-texturing and hybrid micro/nano-texturing with micro-holes (concave-hybrid-pattern) or micro-pillars (convex-hybrid-pattern), were applied to GaN-based light-emitting diodes (LEDs). The nano-texturing was realized by maskless wet-etching, and the micro-texturing was achieved by standard photolithography and wet-etching. Compared to LED chips with flat ITO surface, those with nano-pattern, concave-hybrid-pattern, and convex-hybrid-pattern exhibit enhancement of 11.3%, 15.8%, and 17.9%, respectively, for the light-output powers at 20 mA. The electrical performance has no degradation. Moreover, the convex-hybrid-pattern show higher light-output efficiency under small injection current, while the concave-hybrid-pattern exhibit better light-output efficiency at large injection current. The light-extraction efficiency is simulated by use of two-dimensional finite difference time domain method, and the numerical results are consistent with the experiments.
- light-emitting diodes,
- hybrid micro/nano-textured,
- indium-tin-oxide,
- light-output

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References(16)

References

[1]	Zhmakin A I. Enhancement of light extraction from light emitting diodes. Phys Rep, 2011, 498:189 doi: 10.1016/j.physrep.2010.11.001
[2]	Pan S M, Tu R C, Fan Y M, et al. Improvement of InGaN-GaN light-emitting diodes with surface-textured indium-tin-oxide transparent ohmic contacts. IEEE Photon Tech Lett, 2003, 15(5):649 doi: 10.1109/LPT.2003.809985
[3]	Wang P, Cao B, Wei W, et al. Improved light extraction of GaN-based light-emitting diodes by ITO patterning with optimization design. Solid-State Electron, 2010, 54:283 doi: 10.1016/j.sse.2009.10.005
[4]	Tsai C F, Su Y K, Lin C L. Improvement in external quantum efficiency of InGaN-based LEDs by micro-textured surface with different geometric patterns. J Electrochem Soc, 2012, 159(2):H151 doi: 10.1149/2.055202jes
[5]	Chang S J, Shen C F, Chen W S, et al. Nitride-based light emitting diodes with indium tin oxide electrode patterned by imprint lithography. Appl Phys Lett, 2007, 91:013504 doi: 10.1063/1.2753726
[6]	Leem D S, Cho J, Sone C, et al. Light-output enhancement of GaN-based light-emitting diodes by using hole-patterned transparent indium tin oxide electrodes. J Appl Phys, 2005, 98:076107. doi: 10.1063/1.2081117
[7]	Horng R H, Yang C C, Wu J Y, et al. GaN-based light-emitting diodes with indium tin oxide texturing window layers using natural lithography. Appl Phys Lett, 2005, 86:221101 doi: 10.1063/1.1940723
[8]	He Anhe, Zhang Yong, Zhu Xuehui, et al. Improved light extraction of GaN-based light-emitting diodes with surface-textured indium tin oxide electrodes by nickel nanoparticle mask dry-etching. Chin Phys B, 2010, 19(6):068101 doi: 10.1088/1674-1056/19/6/068101
[9]	Liao C, Wu Y S. InGaN-GaN light emitting diode performance improved by roughening indium tin oxide window layer via natural lithography. Electrochem Solid State Lett, 2010, 13(1):J8 doi: 10.1149/1.3257601
[10]	Leem D S, Lee T, Seong T Y. Enhancement of the light output of GaN-based light-emitting diodes with surface-patterned ITO electrodes by maskless wet-etching. Solid-State Electron, 2007, 51:793 doi: 10.1016/j.sse.2007.02.038
[11]	Kang J H, Kim H G, Ryu J H, et al. Enhancement of light output power in InGaN/GaN LEDs with nanoroughed hemispherical indium tin oxide transparent ohmic contacts. Electrochem Solid State Lett, 2010, 13(2):D1 doi: 10.1149/1.3261741
[12]	Kang J H, Ryu J H, Kim H K, et al. Comparison of various surface textured layer in InGaN LEDs for high light extraction efficiency. Opt Express, 2011, 19(4):3637 doi: 10.1364/OE.19.003637
[13]	Kang J H, Kim H G, Kim H K, et al. Improvement of light output power in InGaN/GaN light-emitting diodes with a nanotextured GaN surface using indium tin oxide nanospheres. Jpn J Appl Phys, 2009, 48:102104 doi: 10.1143/JJAP.48.102104
[14]	Li S, Kuo D S, Liu C H, et al. Efficiency improvement of GaN-based light-emitting diodes by direct wet etching of indium-tin-oxide layer. IET Optoelectron, 2012, 6(6):303 doi: 10.1049/iet-opt.2012.0019
[15]	Huh C, Lee J M, Kim D J, et al. Improvement in light-output efficiency of InGaN/GaN multiple-quantum well light-emitting diodes by current blocking layer. J Appl Phys, 2002, 92(5):2248 doi: 10.1063/1.1497467
[16]	Pan J W, Tsai P J, Chang K D, et al. Light extraction efficiency analysis of GaN-based light-emitting diodes with nanopatterned sapphire substrates. Appl Opt, 2013, 52(7):1358 doi: 10.1364/AO.52.001358

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