Abstract

We report GaN-based near ultraviolet (UV) light emitting diode (LED) that combines indium tin oxide (ITO) nanodot nodes with two-dimensional graphene film as a UV-transparent current spreading electrode (TCSE) to give rise to excellent UV emission efficiency. The light output power of 380 nm emitting UV-LEDs with graphene film on ITO nanodot nodes as TCSE was enhanced remarkably compared to conventional TCSE. The increase of the light output power is attributed to high UV transmittance of graphene, effective current spreading and injection, and texturing effect by ITO nanodots.

© 2011 OSA

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  1. A. Khan, K. Balakrishnan, and T. Katona, “Ultraviolet light-emitting diodes based on group three nitrides,” Nat. Photonics 2(2), 77–84 (2008).
    [CrossRef]
  2. N. F. Gardner, G. O. Muller, Y. C. Shen, G. Chen, S. Watanabe, W. Gotz, and M. R. Krames, “Blue emitting InGaN–GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200 A/cm2,” Appl. Phys. Lett. 91(24), 243506-1–243506-3 (2007).
  3. W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, “Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off,” Appl. Phys. Lett. 75(10), 1360–1362 (1999).
    [CrossRef]
  4. 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]
  5. D. W. Kim, H. Y. Lee, G. Y. Yeom, and Y. J. Sung, “A study of transparent contact to vertical GaN-based light-emitting diodes,” J. Appl. Phys. 98(5), 0531021–0531024 (2005).
  6. T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).
  7. J.-K. Sheu, M.-L. Lee, Y. S. Lu, and K. W. Shu, “Ga-Doped ZnO Transparent Conductive Oxide Films Applied to GaN-Based Light-Emitting Diodes for Improving Light Extraction Efficiency,” IEEE J. Quantum Electron. 44(12), 1211–1218 (2008).
    [CrossRef]
  8. T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D. M. Jeon, J. W. Kim, and Y. C. Kim, “Enhanced optical power and low forward voltage of GaN-based light-emitting diodes with Ga-doped ZnO transparent conducting layer,” Appl. Phys. Lett. 96(5), 051124-1–051124-3 (2010).
  9. S. H. Tu, C. J. Lan, S. H. Wang, M. L. Lee, K. H. Chang, R. M. Lin, J. Y. Chang, and J. K. Sheu, “InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer,” Appl. Phys. Lett. 96(13), 133504-1–133504-3 (2010).
  10. K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science 306(5696), 666–669 (2004).
    [CrossRef] [PubMed]
  11. F. Bonaccorso, Z. Sun, T. Hasan, and A. C. Ferrari, “Graphene photonics and optoelectronics,” Nat. Photonics 4(9), 611–622 (2010).
    [CrossRef]
  12. G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).
  13. T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).
  14. X. Wang, L. Zhi, and K. Mullen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett. 8(1), 323–327 (2008).
    [CrossRef] [PubMed]
  15. T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
    [CrossRef]
  16. Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, and R. S. Ruoff, “Graphene and graphene oxide: synthesis, properties, and applications,” Adv. Mater. (Deerfield Beach Fla.) 22(35), 3906–3924 (2010).
    [CrossRef] [PubMed]
  17. W. S. Hummers and R. E. Offeman, “Preparation of Graphitic Oxide,” J. Am. Chem. Soc. 80(6), 1339–1339 (1958).
    [CrossRef]
  18. F. Guneş, H.-J. Shin, C. Biswas, G. H. Han, E. S. Kim, S. J. Chae, J. Y. Choi, and Y. H. Lee, “Layer-by-layer doping of few-layer graphene film,” ACS Nano 4(8), 4595–4600 (2010).
    [CrossRef] [PubMed]
  19. T. V. Cuong, V. H. Pham, Q. T. Tran, S. H. Hahn, J. S. Chung, E. W. Shin, and E. J. Kim, “Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide,” Mater. Lett. 64(3), 399–401 (2010).
    [CrossRef]
  20. V. H. Pham, T. V. Cuong, S. H. Hur, E. W. Shin, J. S. Kim, J. S. Chung, and E. J. Kim, “Fast and simple fabrication of a large transparent chemically-converted graphene film by spray-coating,” Carbon 48(7), 1945–1951 (2010).
    [CrossRef]
  21. Z. Luo, Y. Lu, L. A. Somers, and A. T. C. Johnson, “High yield preparation of macroscopic graphene oxide membranes,” J. Am. Chem. Soc. 131(3), 898–899 (2009).
    [CrossRef] [PubMed]
  22. D. Li, M. B. Müller, S. Gilje, R. B. Kaner, and G. G. Wallace, “Processable aqueous dispersions of graphene nanosheets,” Nat. Nanotechnol. 3(2), 101–105 (2008).
    [CrossRef] [PubMed]
  23. X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
    [CrossRef] [PubMed]
  24. H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
    [CrossRef]
  25. P. Guéret, P. Buchmann, K. Daetwyler, and P. Vettiger, “Resistance of very small area ohmic contacts on GaAs,” Appl. Phys. Lett. 55(17), 1735–1737 (1989).
    [CrossRef]
  26. H. W. Choi, C. W. Jeon, M. D. Dawson, P. R. Edwards, R. W. Martin, and S. Tripathy, “Mechanism of enhanced light output efficiency in InGaN-based microlight emitting diodes,” J. Appl. Phys. 93(10), 5978–5982 (2003).
    [CrossRef]

2011

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

2010

F. Bonaccorso, Z. Sun, T. Hasan, and A. C. Ferrari, “Graphene photonics and optoelectronics,” Nat. Photonics 4(9), 611–622 (2010).
[CrossRef]

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

F. Guneş, H.-J. Shin, C. Biswas, G. H. Han, E. S. Kim, S. J. Chae, J. Y. Choi, and Y. H. Lee, “Layer-by-layer doping of few-layer graphene film,” ACS Nano 4(8), 4595–4600 (2010).
[CrossRef] [PubMed]

T. V. Cuong, V. H. Pham, Q. T. Tran, S. H. Hahn, J. S. Chung, E. W. Shin, and E. J. Kim, “Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide,” Mater. Lett. 64(3), 399–401 (2010).
[CrossRef]

V. H. Pham, T. V. Cuong, S. H. Hur, E. W. Shin, J. S. Kim, J. S. Chung, and E. J. Kim, “Fast and simple fabrication of a large transparent chemically-converted graphene film by spray-coating,” Carbon 48(7), 1945–1951 (2010).
[CrossRef]

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D. M. Jeon, J. W. Kim, and Y. C. Kim, “Enhanced optical power and low forward voltage of GaN-based light-emitting diodes with Ga-doped ZnO transparent conducting layer,” Appl. Phys. Lett. 96(5), 051124-1–051124-3 (2010).

S. H. Tu, C. J. Lan, S. H. Wang, M. L. Lee, K. H. Chang, R. M. Lin, J. Y. Chang, and J. K. Sheu, “InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer,” Appl. Phys. Lett. 96(13), 133504-1–133504-3 (2010).

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, and R. S. Ruoff, “Graphene and graphene oxide: synthesis, properties, and applications,” Adv. Mater. (Deerfield Beach Fla.) 22(35), 3906–3924 (2010).
[CrossRef] [PubMed]

2009

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Z. Luo, Y. Lu, L. A. Somers, and A. T. C. Johnson, “High yield preparation of macroscopic graphene oxide membranes,” J. Am. Chem. Soc. 131(3), 898–899 (2009).
[CrossRef] [PubMed]

2008

D. Li, M. B. Müller, S. Gilje, R. B. Kaner, and G. G. Wallace, “Processable aqueous dispersions of graphene nanosheets,” Nat. Nanotechnol. 3(2), 101–105 (2008).
[CrossRef] [PubMed]

X. Wang, L. Zhi, and K. Mullen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett. 8(1), 323–327 (2008).
[CrossRef] [PubMed]

J.-K. Sheu, M.-L. Lee, Y. S. Lu, and K. W. Shu, “Ga-Doped ZnO Transparent Conductive Oxide Films Applied to GaN-Based Light-Emitting Diodes for Improving Light Extraction Efficiency,” IEEE J. Quantum Electron. 44(12), 1211–1218 (2008).
[CrossRef]

A. Khan, K. Balakrishnan, and T. Katona, “Ultraviolet light-emitting diodes based on group three nitrides,” Nat. Photonics 2(2), 77–84 (2008).
[CrossRef]

2007

N. F. Gardner, G. O. Muller, Y. C. Shen, G. Chen, S. Watanabe, W. Gotz, and M. R. Krames, “Blue emitting InGaN–GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200 A/cm2,” Appl. Phys. Lett. 91(24), 243506-1–243506-3 (2007).

2005

D. W. Kim, H. Y. Lee, G. Y. Yeom, and Y. J. Sung, “A study of transparent contact to vertical GaN-based light-emitting diodes,” J. Appl. Phys. 98(5), 0531021–0531024 (2005).

2004

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]

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science 306(5696), 666–669 (2004).
[CrossRef] [PubMed]

2003

H. W. Choi, C. W. Jeon, M. D. Dawson, P. R. Edwards, R. W. Martin, and S. Tripathy, “Mechanism of enhanced light output efficiency in InGaN-based microlight emitting diodes,” J. Appl. Phys. 93(10), 5978–5982 (2003).
[CrossRef]

1999

H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
[CrossRef]

W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, “Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off,” Appl. Phys. Lett. 75(10), 1360–1362 (1999).
[CrossRef]

1989

P. Guéret, P. Buchmann, K. Daetwyler, and P. Vettiger, “Resistance of very small area ohmic contacts on GaAs,” Appl. Phys. Lett. 55(17), 1735–1737 (1989).
[CrossRef]

1958

W. S. Hummers and R. E. Offeman, “Preparation of Graphitic Oxide,” J. Am. Chem. Soc. 80(6), 1339–1339 (1958).
[CrossRef]

Ago, H.

H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
[CrossRef]

An, J. H.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Balakrishnan, K.

A. Khan, K. Balakrishnan, and T. Katona, “Ultraviolet light-emitting diodes based on group three nitrides,” Nat. Photonics 2(2), 77–84 (2008).
[CrossRef]

Banerjee, S. K.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Biswas, C.

F. Guneş, H.-J. Shin, C. Biswas, G. H. Han, E. S. Kim, S. J. Chae, J. Y. Choi, and Y. H. Lee, “Layer-by-layer doping of few-layer graphene film,” ACS Nano 4(8), 4595–4600 (2010).
[CrossRef] [PubMed]

Bonaccorso, F.

F. Bonaccorso, Z. Sun, T. Hasan, and A. C. Ferrari, “Graphene photonics and optoelectronics,” Nat. Photonics 4(9), 611–622 (2010).
[CrossRef]

Bour, D. P.

W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, “Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off,” Appl. Phys. Lett. 75(10), 1360–1362 (1999).
[CrossRef]

Buchmann, P.

P. Guéret, P. Buchmann, K. Daetwyler, and P. Vettiger, “Resistance of very small area ohmic contacts on GaAs,” Appl. Phys. Lett. 55(17), 1735–1737 (1989).
[CrossRef]

Cacialli, F.

H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
[CrossRef]

Cai, W.

Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, and R. S. Ruoff, “Graphene and graphene oxide: synthesis, properties, and applications,” Adv. Mater. (Deerfield Beach Fla.) 22(35), 3906–3924 (2010).
[CrossRef] [PubMed]

Cai, W. W.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Chae, S. J.

F. Guneş, H.-J. Shin, C. Biswas, G. H. Han, E. S. Kim, S. J. Chae, J. Y. Choi, and Y. H. Lee, “Layer-by-layer doping of few-layer graphene film,” ACS Nano 4(8), 4595–4600 (2010).
[CrossRef] [PubMed]

Chang, J. Y.

S. H. Tu, C. J. Lan, S. H. Wang, M. L. Lee, K. H. Chang, R. M. Lin, J. Y. Chang, and J. K. Sheu, “InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer,” Appl. Phys. Lett. 96(13), 133504-1–133504-3 (2010).

Chang, K. H.

S. H. Tu, C. J. Lan, S. H. Wang, M. L. Lee, K. H. Chang, R. M. Lin, J. Y. Chang, and J. K. Sheu, “InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer,” Appl. Phys. Lett. 96(13), 133504-1–133504-3 (2010).

Chen, G.

N. F. Gardner, G. O. Muller, Y. C. Shen, G. Chen, S. Watanabe, W. Gotz, and M. R. Krames, “Blue emitting InGaN–GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200 A/cm2,” Appl. Phys. Lett. 91(24), 243506-1–243506-3 (2007).

Cheung, N. W.

W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, “Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off,” Appl. Phys. Lett. 75(10), 1360–1362 (1999).
[CrossRef]

Cho, C. Y.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Choe, M. H.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Choi, H. W.

H. W. Choi, C. W. Jeon, M. D. Dawson, P. R. Edwards, R. W. Martin, and S. Tripathy, “Mechanism of enhanced light output efficiency in InGaN-based microlight emitting diodes,” J. Appl. Phys. 93(10), 5978–5982 (2003).
[CrossRef]

Choi, J. Y.

F. Guneş, H.-J. Shin, C. Biswas, G. H. Han, E. S. Kim, S. J. Chae, J. Y. Choi, and Y. H. Lee, “Layer-by-layer doping of few-layer graphene film,” ACS Nano 4(8), 4595–4600 (2010).
[CrossRef] [PubMed]

Choi, Y. R.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

Choi, Y.-S.

T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D. M. Jeon, J. W. Kim, and Y. C. Kim, “Enhanced optical power and low forward voltage of GaN-based light-emitting diodes with Ga-doped ZnO transparent conducting layer,” Appl. Phys. Lett. 96(5), 051124-1–051124-3 (2010).

Chung, J. S.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

V. H. Pham, T. V. Cuong, S. H. Hur, E. W. Shin, J. S. Kim, J. S. Chung, and E. J. Kim, “Fast and simple fabrication of a large transparent chemically-converted graphene film by spray-coating,” Carbon 48(7), 1945–1951 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, Q. T. Tran, S. H. Hahn, J. S. Chung, E. W. Shin, and E. J. Kim, “Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide,” Mater. Lett. 64(3), 399–401 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Colombo, L.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Cuong, T. V.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

V. H. Pham, T. V. Cuong, S. H. Hur, E. W. Shin, J. S. Kim, J. S. Chung, and E. J. Kim, “Fast and simple fabrication of a large transparent chemically-converted graphene film by spray-coating,” Carbon 48(7), 1945–1951 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, Q. T. Tran, S. H. Hahn, J. S. Chung, E. W. Shin, and E. J. Kim, “Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide,” Mater. Lett. 64(3), 399–401 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Daetwyler, K.

P. Guéret, P. Buchmann, K. Daetwyler, and P. Vettiger, “Resistance of very small area ohmic contacts on GaAs,” Appl. Phys. Lett. 55(17), 1735–1737 (1989).
[CrossRef]

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H. W. Choi, C. W. Jeon, M. D. Dawson, P. R. Edwards, R. W. Martin, and S. Tripathy, “Mechanism of enhanced light output efficiency in InGaN-based microlight emitting diodes,” J. Appl. Phys. 93(10), 5978–5982 (2003).
[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]

Dubonos, S. V.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science 306(5696), 666–669 (2004).
[CrossRef] [PubMed]

Edwards, P. R.

H. W. Choi, C. W. Jeon, M. D. Dawson, P. R. Edwards, R. W. Martin, and S. Tripathy, “Mechanism of enhanced light output efficiency in InGaN-based microlight emitting diodes,” J. Appl. Phys. 93(10), 5978–5982 (2003).
[CrossRef]

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F. Bonaccorso, Z. Sun, T. Hasan, and A. C. Ferrari, “Graphene photonics and optoelectronics,” Nat. Photonics 4(9), 611–622 (2010).
[CrossRef]

Firsov, A. A.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science 306(5696), 666–669 (2004).
[CrossRef] [PubMed]

Friend, R. H.

H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
[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]

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]

Gardner, N. F.

N. F. Gardner, G. O. Muller, Y. C. Shen, G. Chen, S. Watanabe, W. Gotz, and M. R. Krames, “Blue emitting InGaN–GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200 A/cm2,” Appl. Phys. Lett. 91(24), 243506-1–243506-3 (2007).

Geim, A. K.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science 306(5696), 666–669 (2004).
[CrossRef] [PubMed]

Gilje, S.

D. Li, M. B. Müller, S. Gilje, R. B. Kaner, and G. G. Wallace, “Processable aqueous dispersions of graphene nanosheets,” Nat. Nanotechnol. 3(2), 101–105 (2008).
[CrossRef] [PubMed]

Gotz, W.

N. F. Gardner, G. O. Muller, Y. C. Shen, G. Chen, S. Watanabe, W. Gotz, and M. R. Krames, “Blue emitting InGaN–GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200 A/cm2,” Appl. Phys. Lett. 91(24), 243506-1–243506-3 (2007).

Grigorieva, I. V.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science 306(5696), 666–669 (2004).
[CrossRef] [PubMed]

Guéret, P.

P. Guéret, P. Buchmann, K. Daetwyler, and P. Vettiger, “Resistance of very small area ohmic contacts on GaAs,” Appl. Phys. Lett. 55(17), 1735–1737 (1989).
[CrossRef]

Gunes, F.

F. Guneş, H.-J. Shin, C. Biswas, G. H. Han, E. S. Kim, S. J. Chae, J. Y. Choi, and Y. H. Lee, “Layer-by-layer doping of few-layer graphene film,” ACS Nano 4(8), 4595–4600 (2010).
[CrossRef] [PubMed]

Hahn, S. H.

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, Q. T. Tran, S. H. Hahn, J. S. Chung, E. W. Shin, and E. J. Kim, “Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide,” Mater. Lett. 64(3), 399–401 (2010).
[CrossRef]

Han, G. H.

F. Guneş, H.-J. Shin, C. Biswas, G. H. Han, E. S. Kim, S. J. Chae, J. Y. Choi, and Y. H. Lee, “Layer-by-layer doping of few-layer graphene film,” ACS Nano 4(8), 4595–4600 (2010).
[CrossRef] [PubMed]

Hasan, T.

F. Bonaccorso, Z. Sun, T. Hasan, and A. C. Ferrari, “Graphene photonics and optoelectronics,” Nat. Photonics 4(9), 611–622 (2010).
[CrossRef]

Hong, B. H.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Hong, C.-H.

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

Hong, W. K.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

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]

Huh, J. S.

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Hummers, W. S.

W. S. Hummers and R. E. Offeman, “Preparation of Graphitic Oxide,” J. Am. Chem. Soc. 80(6), 1339–1339 (1958).
[CrossRef]

Hur, S. H.

V. H. Pham, T. V. Cuong, S. H. Hur, E. W. Shin, J. S. Kim, J. S. Chung, and E. J. Kim, “Fast and simple fabrication of a large transparent chemically-converted graphene film by spray-coating,” Carbon 48(7), 1945–1951 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Jeon, C. W.

H. W. Choi, C. W. Jeon, M. D. Dawson, P. R. Edwards, R. W. Martin, and S. Tripathy, “Mechanism of enhanced light output efficiency in InGaN-based microlight emitting diodes,” J. Appl. Phys. 93(10), 5978–5982 (2003).
[CrossRef]

Jeon, D. M.

T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D. M. Jeon, J. W. Kim, and Y. C. Kim, “Enhanced optical power and low forward voltage of GaN-based light-emitting diodes with Ga-doped ZnO transparent conducting layer,” Appl. Phys. Lett. 96(5), 051124-1–051124-3 (2010).

Jeong, H.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

Jeong, J.-H.

T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D. M. Jeon, J. W. Kim, and Y. C. Kim, “Enhanced optical power and low forward voltage of GaN-based light-emitting diodes with Ga-doped ZnO transparent conducting layer,” Appl. Phys. Lett. 96(5), 051124-1–051124-3 (2010).

Jiang, D.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science 306(5696), 666–669 (2004).
[CrossRef] [PubMed]

Jo, G. H.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Johnson, A. T. C.

Z. Luo, Y. Lu, L. A. Somers, and A. T. C. Johnson, “High yield preparation of macroscopic graphene oxide membranes,” J. Am. Chem. Soc. 131(3), 898–899 (2009).
[CrossRef] [PubMed]

Johnson, N. M.

W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, “Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off,” Appl. Phys. Lett. 75(10), 1360–1362 (1999).
[CrossRef]

Jung, I.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Kahng, Y. H.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Kaner, R. B.

D. Li, M. B. Müller, S. Gilje, R. B. Kaner, and G. G. Wallace, “Processable aqueous dispersions of graphene nanosheets,” Nat. Nanotechnol. 3(2), 101–105 (2008).
[CrossRef] [PubMed]

Kang, J.-W.

T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D. M. Jeon, J. W. Kim, and Y. C. Kim, “Enhanced optical power and low forward voltage of GaN-based light-emitting diodes with Ga-doped ZnO transparent conducting layer,” Appl. Phys. Lett. 96(5), 051124-1–051124-3 (2010).

Katona, T.

A. Khan, K. Balakrishnan, and T. Katona, “Ultraviolet light-emitting diodes based on group three nitrides,” Nat. Photonics 2(2), 77–84 (2008).
[CrossRef]

Khan, A.

A. Khan, K. Balakrishnan, and T. Katona, “Ultraviolet light-emitting diodes based on group three nitrides,” Nat. Photonics 2(2), 77–84 (2008).
[CrossRef]

Kim, D. W.

D. W. Kim, H. Y. Lee, G. Y. Yeom, and Y. J. Sung, “A study of transparent contact to vertical GaN-based light-emitting diodes,” J. Appl. Phys. 98(5), 0531021–0531024 (2005).

Kim, E. J.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

V. H. Pham, T. V. Cuong, S. H. Hur, E. W. Shin, J. S. Kim, J. S. Chung, and E. J. Kim, “Fast and simple fabrication of a large transparent chemically-converted graphene film by spray-coating,” Carbon 48(7), 1945–1951 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, Q. T. Tran, S. H. Hahn, J. S. Chung, E. W. Shin, and E. J. Kim, “Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide,” Mater. Lett. 64(3), 399–401 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Kim, E. S.

F. Guneş, H.-J. Shin, C. Biswas, G. H. Han, E. S. Kim, S. J. Chae, J. Y. Choi, and Y. H. Lee, “Layer-by-layer doping of few-layer graphene film,” ACS Nano 4(8), 4595–4600 (2010).
[CrossRef] [PubMed]

Kim, H.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

Kim, J. D.

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

Kim, J. H.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Kim, J. S.

V. H. Pham, T. V. Cuong, S. H. Hur, E. W. Shin, J. S. Kim, J. S. Chung, and E. J. Kim, “Fast and simple fabrication of a large transparent chemically-converted graphene film by spray-coating,” Carbon 48(7), 1945–1951 (2010).
[CrossRef]

Kim, J. W.

T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D. M. Jeon, J. W. Kim, and Y. C. Kim, “Enhanced optical power and low forward voltage of GaN-based light-emitting diodes with Ga-doped ZnO transparent conducting layer,” Appl. Phys. Lett. 96(5), 051124-1–051124-3 (2010).

Kim, S.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Kim, T. W.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Kim, Y. C.

T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D. M. Jeon, J. W. Kim, and Y. C. Kim, “Enhanced optical power and low forward voltage of GaN-based light-emitting diodes with Ga-doped ZnO transparent conducting layer,” Appl. Phys. Lett. 96(5), 051124-1–051124-3 (2010).

Kneissl, M.

W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, “Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off,” Appl. Phys. Lett. 75(10), 1360–1362 (1999).
[CrossRef]

Kohl, P. A.

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Krames, M. R.

N. F. Gardner, G. O. Muller, Y. C. Shen, G. Chen, S. Watanabe, W. Gotz, and M. R. Krames, “Blue emitting InGaN–GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200 A/cm2,” Appl. Phys. Lett. 91(24), 243506-1–243506-3 (2007).

Kugler, T.

H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
[CrossRef]

Lan, C. J.

S. H. Tu, C. J. Lan, S. H. Wang, M. L. Lee, K. H. Chang, R. M. Lin, J. Y. Chang, and J. K. Sheu, “InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer,” Appl. Phys. Lett. 96(13), 133504-1–133504-3 (2010).

Lee, H. Y.

D. W. Kim, H. Y. Lee, G. Y. Yeom, and Y. J. Sung, “A study of transparent contact to vertical GaN-based light-emitting diodes,” J. Appl. Phys. 98(5), 0531021–0531024 (2005).

Lee, K. J.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

Lee, M. L.

S. H. Tu, C. J. Lan, S. H. Wang, M. L. Lee, K. H. Chang, R. M. Lin, J. Y. Chang, and J. K. Sheu, “InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer,” Appl. Phys. Lett. 96(13), 133504-1–133504-3 (2010).

Lee, M.-L.

J.-K. Sheu, M.-L. Lee, Y. S. Lu, and K. W. Shu, “Ga-Doped ZnO Transparent Conductive Oxide Films Applied to GaN-Based Light-Emitting Diodes for Improving Light Extraction Efficiency,” IEEE J. Quantum Electron. 44(12), 1211–1218 (2008).
[CrossRef]

Lee, S. C.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Lee, T. H.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Lee, T. S.

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

Lee, Y. H.

F. Guneş, H.-J. Shin, C. Biswas, G. H. Han, E. S. Kim, S. J. Chae, J. Y. Choi, and Y. H. Lee, “Layer-by-layer doping of few-layer graphene film,” ACS Nano 4(8), 4595–4600 (2010).
[CrossRef] [PubMed]

Lee, Y. S.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

Li, D.

D. Li, M. B. Müller, S. Gilje, R. B. Kaner, and G. G. Wallace, “Processable aqueous dispersions of graphene nanosheets,” Nat. Nanotechnol. 3(2), 101–105 (2008).
[CrossRef] [PubMed]

Li, X.

Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, and R. S. Ruoff, “Graphene and graphene oxide: synthesis, properties, and applications,” Adv. Mater. (Deerfield Beach Fla.) 22(35), 3906–3924 (2010).
[CrossRef] [PubMed]

Li, X. S.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Lin, R. M.

S. H. Tu, C. J. Lan, S. H. Wang, M. L. Lee, K. H. Chang, R. M. Lin, J. Y. Chang, and J. K. Sheu, “InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer,” Appl. Phys. Lett. 96(13), 133504-1–133504-3 (2010).

Lu, Y.

Z. Luo, Y. Lu, L. A. Somers, and A. T. C. Johnson, “High yield preparation of macroscopic graphene oxide membranes,” J. Am. Chem. Soc. 131(3), 898–899 (2009).
[CrossRef] [PubMed]

Lu, Y. S.

J.-K. Sheu, M.-L. Lee, Y. S. Lu, and K. W. Shu, “Ga-Doped ZnO Transparent Conductive Oxide Films Applied to GaN-Based Light-Emitting Diodes for Improving Light Extraction Efficiency,” IEEE J. Quantum Electron. 44(12), 1211–1218 (2008).
[CrossRef]

Luo, Z.

Z. Luo, Y. Lu, L. A. Somers, and A. T. C. Johnson, “High yield preparation of macroscopic graphene oxide membranes,” J. Am. Chem. Soc. 131(3), 898–899 (2009).
[CrossRef] [PubMed]

Martin, R. W.

H. W. Choi, C. W. Jeon, M. D. Dawson, P. R. Edwards, R. W. Martin, and S. Tripathy, “Mechanism of enhanced light output efficiency in InGaN-based microlight emitting diodes,” J. Appl. Phys. 93(10), 5978–5982 (2003).
[CrossRef]

Mei, P.

W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, “Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off,” Appl. Phys. Lett. 75(10), 1360–1362 (1999).
[CrossRef]

Morozov, S. V.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science 306(5696), 666–669 (2004).
[CrossRef] [PubMed]

Mullen, K.

X. Wang, L. Zhi, and K. Mullen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett. 8(1), 323–327 (2008).
[CrossRef] [PubMed]

Muller, G. O.

N. F. Gardner, G. O. Muller, Y. C. Shen, G. Chen, S. Watanabe, W. Gotz, and M. R. Krames, “Blue emitting InGaN–GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200 A/cm2,” Appl. Phys. Lett. 91(24), 243506-1–243506-3 (2007).

Müller, M. B.

D. Li, M. B. Müller, S. Gilje, R. B. Kaner, and G. G. Wallace, “Processable aqueous dispersions of graphene nanosheets,” Nat. Nanotechnol. 3(2), 101–105 (2008).
[CrossRef] [PubMed]

Murali, S.

Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, and R. S. Ruoff, “Graphene and graphene oxide: synthesis, properties, and applications,” Adv. Mater. (Deerfield Beach Fla.) 22(35), 3906–3924 (2010).
[CrossRef] [PubMed]

Nah, J.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

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]

Novoselov, K. S.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science 306(5696), 666–669 (2004).
[CrossRef] [PubMed]

Offeman, R. E.

W. S. Hummers and R. E. Offeman, “Preparation of Graphitic Oxide,” J. Am. Chem. Soc. 80(6), 1339–1339 (1958).
[CrossRef]

Oh, T. S.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

Ono, Y.

H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
[CrossRef]

Park, A. H.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

Park, S. J.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Park, S.-J.

T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D. M. Jeon, J. W. Kim, and Y. C. Kim, “Enhanced optical power and low forward voltage of GaN-based light-emitting diodes with Ga-doped ZnO transparent conducting layer,” Appl. Phys. Lett. 96(5), 051124-1–051124-3 (2010).

Park, T.-Y.

T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D. M. Jeon, J. W. Kim, and Y. C. Kim, “Enhanced optical power and low forward voltage of GaN-based light-emitting diodes with Ga-doped ZnO transparent conducting layer,” Appl. Phys. Lett. 96(5), 051124-1–051124-3 (2010).

Park, W. J.

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Petritsch, K.

H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
[CrossRef]

Pham, V. H.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

V. H. Pham, T. V. Cuong, S. H. Hur, E. W. Shin, J. S. Kim, J. S. Chung, and E. J. Kim, “Fast and simple fabrication of a large transparent chemically-converted graphene film by spray-coating,” Carbon 48(7), 1945–1951 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, Q. T. Tran, S. H. Hahn, J. S. Chung, E. W. Shin, and E. J. Kim, “Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide,” Mater. Lett. 64(3), 399–401 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Piner, R. D.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Potts, J. R.

Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, and R. S. Ruoff, “Graphene and graphene oxide: synthesis, properties, and applications,” Adv. Mater. (Deerfield Beach Fla.) 22(35), 3906–3924 (2010).
[CrossRef] [PubMed]

Romano, L. T.

W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, “Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off,” Appl. Phys. Lett. 75(10), 1360–1362 (1999).
[CrossRef]

Rue, G. H.

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Rue, G. S.

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Ruoff, R. S.

Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, and R. S. Ruoff, “Graphene and graphene oxide: synthesis, properties, and applications,” Adv. Mater. (Deerfield Beach Fla.) 22(35), 3906–3924 (2010).
[CrossRef] [PubMed]

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Salaneck, W. R.

H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
[CrossRef]

Sands, T.

W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, “Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off,” Appl. Phys. Lett. 75(10), 1360–1362 (1999).
[CrossRef]

Seo, T. H.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

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, Y. C.

N. F. Gardner, G. O. Muller, Y. C. Shen, G. Chen, S. Watanabe, W. Gotz, and M. R. Krames, “Blue emitting InGaN–GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200 A/cm2,” Appl. Phys. Lett. 91(24), 243506-1–243506-3 (2007).

Sheu, J. K.

S. H. Tu, C. J. Lan, S. H. Wang, M. L. Lee, K. H. Chang, R. M. Lin, J. Y. Chang, and J. K. Sheu, “InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer,” Appl. Phys. Lett. 96(13), 133504-1–133504-3 (2010).

Sheu, J.-K.

J.-K. Sheu, M.-L. Lee, Y. S. Lu, and K. W. Shu, “Ga-Doped ZnO Transparent Conductive Oxide Films Applied to GaN-Based Light-Emitting Diodes for Improving Light Extraction Efficiency,” IEEE J. Quantum Electron. 44(12), 1211–1218 (2008).
[CrossRef]

Shin, E. W.

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

V. H. Pham, T. V. Cuong, S. H. Hur, E. W. Shin, J. S. Kim, J. S. Chung, and E. J. Kim, “Fast and simple fabrication of a large transparent chemically-converted graphene film by spray-coating,” Carbon 48(7), 1945–1951 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, Q. T. Tran, S. H. Hahn, J. S. Chung, E. W. Shin, and E. J. Kim, “Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide,” Mater. Lett. 64(3), 399–401 (2010).
[CrossRef]

Shin, H.-J.

F. Guneş, H.-J. Shin, C. Biswas, G. H. Han, E. S. Kim, S. J. Chae, J. Y. Choi, and Y. H. Lee, “Layer-by-layer doping of few-layer graphene film,” ACS Nano 4(8), 4595–4600 (2010).
[CrossRef] [PubMed]

Shu, K. W.

J.-K. Sheu, M.-L. Lee, Y. S. Lu, and K. W. Shu, “Ga-Doped ZnO Transparent Conductive Oxide Films Applied to GaN-Based Light-Emitting Diodes for Improving Light Extraction Efficiency,” IEEE J. Quantum Electron. 44(12), 1211–1218 (2008).
[CrossRef]

Somers, L. A.

Z. Luo, Y. Lu, L. A. Somers, and A. T. C. Johnson, “High yield preparation of macroscopic graphene oxide membranes,” J. Am. Chem. Soc. 131(3), 898–899 (2009).
[CrossRef] [PubMed]

Suh, E.-K.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

Suk, J. W.

Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, and R. S. Ruoff, “Graphene and graphene oxide: synthesis, properties, and applications,” Adv. Mater. (Deerfield Beach Fla.) 22(35), 3906–3924 (2010).
[CrossRef] [PubMed]

Sun, Z.

F. Bonaccorso, Z. Sun, T. Hasan, and A. C. Ferrari, “Graphene photonics and optoelectronics,” Nat. Photonics 4(9), 611–622 (2010).
[CrossRef]

Sung, Y. J.

D. W. Kim, H. Y. Lee, G. Y. Yeom, and Y. J. Sung, “A study of transparent contact to vertical GaN-based light-emitting diodes,” J. Appl. Phys. 98(5), 0531021–0531024 (2005).

Tanaka, K.

H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
[CrossRef]

Tran, Q. T.

T. V. Cuong, V. H. Pham, Q. T. Tran, S. H. Hahn, J. S. Chung, E. W. Shin, and E. J. Kim, “Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide,” Mater. Lett. 64(3), 399–401 (2010).
[CrossRef]

Tripathy, S.

H. W. Choi, C. W. Jeon, M. D. Dawson, P. R. Edwards, R. W. Martin, and S. Tripathy, “Mechanism of enhanced light output efficiency in InGaN-based microlight emitting diodes,” J. Appl. Phys. 93(10), 5978–5982 (2003).
[CrossRef]

Tu, S. H.

S. H. Tu, C. J. Lan, S. H. Wang, M. L. Lee, K. H. Chang, R. M. Lin, J. Y. Chang, and J. K. Sheu, “InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer,” Appl. Phys. Lett. 96(13), 133504-1–133504-3 (2010).

Tutuc, E.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Velamakanni, A.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Vettiger, P.

P. Guéret, P. Buchmann, K. Daetwyler, and P. Vettiger, “Resistance of very small area ohmic contacts on GaAs,” Appl. Phys. Lett. 55(17), 1735–1737 (1989).
[CrossRef]

Wallace, G. G.

D. Li, M. B. Müller, S. Gilje, R. B. Kaner, and G. G. Wallace, “Processable aqueous dispersions of graphene nanosheets,” Nat. Nanotechnol. 3(2), 101–105 (2008).
[CrossRef] [PubMed]

Wang, S. H.

S. H. Tu, C. J. Lan, S. H. Wang, M. L. Lee, K. H. Chang, R. M. Lin, J. Y. Chang, and J. K. Sheu, “InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer,” Appl. Phys. Lett. 96(13), 133504-1–133504-3 (2010).

Wang, X.

X. Wang, L. Zhi, and K. Mullen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett. 8(1), 323–327 (2008).
[CrossRef] [PubMed]

Watanabe, S.

N. F. Gardner, G. O. Muller, Y. C. Shen, G. Chen, S. Watanabe, W. Gotz, and M. R. Krames, “Blue emitting InGaN–GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200 A/cm2,” Appl. Phys. Lett. 91(24), 243506-1–243506-3 (2007).

Wong, W. S.

W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, “Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off,” Appl. Phys. Lett. 75(10), 1360–1362 (1999).
[CrossRef]

Yamabe, T.

H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
[CrossRef]

Yang, D. X.

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Yeom, G. Y.

D. W. Kim, H. Y. Lee, G. Y. Yeom, and Y. J. Sung, “A study of transparent contact to vertical GaN-based light-emitting diodes,” J. Appl. Phys. 98(5), 0531021–0531024 (2005).

Yoo, D. H.

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Zhang, Y.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science 306(5696), 666–669 (2004).
[CrossRef] [PubMed]

Zhi, L.

X. Wang, L. Zhi, and K. Mullen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett. 8(1), 323–327 (2008).
[CrossRef] [PubMed]

Zhu, Y.

Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, and R. S. Ruoff, “Graphene and graphene oxide: synthesis, properties, and applications,” Adv. Mater. (Deerfield Beach Fla.) 22(35), 3906–3924 (2010).
[CrossRef] [PubMed]

ACS Nano

F. Guneş, H.-J. Shin, C. Biswas, G. H. Han, E. S. Kim, S. J. Chae, J. Y. Choi, and Y. H. Lee, “Layer-by-layer doping of few-layer graphene film,” ACS Nano 4(8), 4595–4600 (2010).
[CrossRef] [PubMed]

Adv. Mater. (Deerfield Beach Fla.)

Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts, and R. S. Ruoff, “Graphene and graphene oxide: synthesis, properties, and applications,” Adv. Mater. (Deerfield Beach Fla.) 22(35), 3906–3924 (2010).
[CrossRef] [PubMed]

Appl. Phys. Lett.

T. H. Seo, K. J. Lee, T. S. Oh, Y. S. Lee, H. Jeong, A. H. Park, H. Kim, Y. R. Choi, E.-K. Suh, T. V. Cuong, V. H. Pham, J. S. Chung, and E. J. Kim, “Graphene network on indium tin oxide nanodot nodes for transparent and current spreading electrode in InGaN/GaN light emitting diode,” Appl. Phys. Lett. 98(25), 251114-1–251114-3 (2011).

N. F. Gardner, G. O. Muller, Y. C. Shen, G. Chen, S. Watanabe, W. Gotz, and M. R. Krames, “Blue emitting InGaN–GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200 A/cm2,” Appl. Phys. Lett. 91(24), 243506-1–243506-3 (2007).

W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, “Fabrication of thin-film InGaN light-emitting diode membranes by laser lift-off,” Appl. Phys. Lett. 75(10), 1360–1362 (1999).
[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]

T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D. M. Jeon, J. W. Kim, and Y. C. Kim, “Enhanced optical power and low forward voltage of GaN-based light-emitting diodes with Ga-doped ZnO transparent conducting layer,” Appl. Phys. Lett. 96(5), 051124-1–051124-3 (2010).

S. H. Tu, C. J. Lan, S. H. Wang, M. L. Lee, K. H. Chang, R. M. Lin, J. Y. Chang, and J. K. Sheu, “InGaN gallium nitride light-emitting diodes with reflective electrode pads and textured gallium-doped ZnO contact layer,” Appl. Phys. Lett. 96(13), 133504-1–133504-3 (2010).

P. Guéret, P. Buchmann, K. Daetwyler, and P. Vettiger, “Resistance of very small area ohmic contacts on GaAs,” Appl. Phys. Lett. 55(17), 1735–1737 (1989).
[CrossRef]

Carbon

V. H. Pham, T. V. Cuong, S. H. Hur, E. W. Shin, J. S. Kim, J. S. Chung, and E. J. Kim, “Fast and simple fabrication of a large transparent chemically-converted graphene film by spray-coating,” Carbon 48(7), 1945–1951 (2010).
[CrossRef]

IEEE J. Quantum Electron.

J.-K. Sheu, M.-L. Lee, Y. S. Lu, and K. W. Shu, “Ga-Doped ZnO Transparent Conductive Oxide Films Applied to GaN-Based Light-Emitting Diodes for Improving Light Extraction Efficiency,” IEEE J. Quantum Electron. 44(12), 1211–1218 (2008).
[CrossRef]

J. Am. Chem. Soc.

W. S. Hummers and R. E. Offeman, “Preparation of Graphitic Oxide,” J. Am. Chem. Soc. 80(6), 1339–1339 (1958).
[CrossRef]

Z. Luo, Y. Lu, L. A. Somers, and A. T. C. Johnson, “High yield preparation of macroscopic graphene oxide membranes,” J. Am. Chem. Soc. 131(3), 898–899 (2009).
[CrossRef] [PubMed]

J. Appl. Phys.

H. W. Choi, C. W. Jeon, M. D. Dawson, P. R. Edwards, R. W. Martin, and S. Tripathy, “Mechanism of enhanced light output efficiency in InGaN-based microlight emitting diodes,” J. Appl. Phys. 93(10), 5978–5982 (2003).
[CrossRef]

D. W. Kim, H. Y. Lee, G. Y. Yeom, and Y. J. Sung, “A study of transparent contact to vertical GaN-based light-emitting diodes,” J. Appl. Phys. 98(5), 0531021–0531024 (2005).

Jpn. J. Appl. Phys.

T. H. Seo, T. S. Oh, T. S. Lee, H. Jeong, J. D. Kim, H. Kim, A. H. Park, K. J. Lee, C.-H. Hong, and E.-K. Suh, “Enhanced Light Extraction in GaN-Based Light Emitting Diodes with Holographically Fabricated Concave Hemisphere-Shaped Patterning on Indium-Tin-Oxide Layer,” Jpn. J. Appl. Phys. 49, 092101-1–092101-3 (2010).

Mater. Lett.

T. V. Cuong, V. H. Pham, Q. T. Tran, S. H. Hahn, J. S. Chung, E. W. Shin, and E. J. Kim, “Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide,” Mater. Lett. 64(3), 399–401 (2010).
[CrossRef]

T. V. Cuong, V. H. Pham, J. S. Chung, E. W. Shin, D. H. Yoo, S. H. Hahn, J. S. Huh, G. H. Rue, E. J. Kim, S. H. Hur, G. S. Rue, E. J. Kim, S. H. Hur, and P. A. Kohl, “Solution-processed ZnO-chemically converted graphene gas sensor,” Mater. Lett. 64(22), 2479–2482 (2010).
[CrossRef]

Nano Lett.

X. Wang, L. Zhi, and K. Mullen, “Transparent, conductive graphene electrodes for dye-sensitized solar cells,” Nano Lett. 8(1), 323–327 (2008).
[CrossRef] [PubMed]

Nanotechnology

G. H. Jo, M. H. Choe, C. Y. Cho, J. H. Kim, W. J. Park, S. C. Lee, W. K. Hong, T. W. Kim, S. J. Park, B. H. Hong, Y. H. Kahng, and T. H. Lee, “Large-scale patterned multi-layer graphene films as transparent conducting electrodes for GaN light-emitting diodes,” Nanotechnology 21, 175201-1–175201-6 (2010).

Nat. Nanotechnol.

D. Li, M. B. Müller, S. Gilje, R. B. Kaner, and G. G. Wallace, “Processable aqueous dispersions of graphene nanosheets,” Nat. Nanotechnol. 3(2), 101–105 (2008).
[CrossRef] [PubMed]

Nat. Photonics

F. Bonaccorso, Z. Sun, T. Hasan, and A. C. Ferrari, “Graphene photonics and optoelectronics,” Nat. Photonics 4(9), 611–622 (2010).
[CrossRef]

A. Khan, K. Balakrishnan, and T. Katona, “Ultraviolet light-emitting diodes based on group three nitrides,” Nat. Photonics 2(2), 77–84 (2008).
[CrossRef]

Science

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films,” Science 306(5696), 666–669 (2004).
[CrossRef] [PubMed]

X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. D. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, “Large-area synthesis of high-quality and uniform graphene films on copper foils,” Science 324(5932), 1312–1314 (2009).
[CrossRef] [PubMed]

Synth. Met.

H. Ago, T. Kugler, F. Cacialli, K. Petritsch, R. H. Friend, W. R. Salaneck, Y. Ono, T. Yamabe, and K. Tanaka, “Work function of purified and oxidised carbon nanotubes,” Synth. Met. 103(1-3), 2494–2495 (1999).
[CrossRef]

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