Abstract

The authors report high-efficiency GaN-based light-emitting diodes (LEDs) fabricated with identical Ag contact formed on both n- and p-layers. Ag contacts thermally annealed at optimized conditions yielded low specific contact resistances of 4.5 × 10−4 and 9.4 × 10−4 Ωcm2, and high optical reflectivity (at 450 nm) of 88.1 and 85.3% for n- and p-contact, respectively. LEDs fabricated with identical Ag contacts formed on both layers showed 31% brighter light output power and nearly the same forward voltages as compared to reference LEDs. This indicates that Ag contact can be used as a reflective electrode for both n- and p-layers, leading to enhanced extraction efficiency and fewer process steps.

© 2013 OSA

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  1. J. O. Song, J.-S. Ha, and T.-Y. Seong, “Ohmic-Contact technology for GaN-based light-emitting diodes: Role of p-type contact,” IEEE Trans. Electron. Dev.57(1), 42–59 (2010).
    [CrossRef]
  2. D. L. Hibbard, S. P. Jung, C. Wang, D. Ullery, Y. S. Zhao, H. P. Lee, W. So, and H. Liu, “Low resistance high reflectance contacts to p-GaN using oxidized Ni/Au and Al or Ag,” Appl. Phys. Lett.83(2), 311 (2003).
    [CrossRef]
  3. J. O. Song, D.-S. Leem, J. S. Kwak, O. H. Nam, Y. Park, and T.-Y. Seong, “Low-resistance and highly-reflective Zn–Ni solid solution/Ag ohmic contacts for flip-chip light-emitting diodes,” Appl. Phys. Lett.83(24), 4990 (2003).
    [CrossRef]
  4. J. K. Kim, T. Gessmann, H. Luo, and E. F. Schubert, “GaInN light-emitting diodes with RuO2/SiO2/Ag omni-directional reflector,” Appl. Phys. Lett.84(22), 4508 (2004).
    [CrossRef]
  5. H. W. Jang and J.-L. Lee, “Low-resistance and high-reflectance Ni/Ag/Ru/Ni/Au ohmic contact on p-type GaN,” Appl. Phys. Lett.85(19), 4421 (2004).
    [CrossRef]
  6. H. W. Jang and J.-L. Lee, “Mechanism for ohmic contact formation of Ni/Ag contacts on p-type GaN,” Appl. Phys. Lett.85(24), 5920 (2004).
    [CrossRef]
  7. J. O. Song, J. S. Kwak, Y. Park, and T.-Y. Seong, “Ohmic and degradation mechanisms of Ag contacts on p-type GaN,” Appl. Phys. Lett.86(6), 062104 (2005).
    [CrossRef]
  8. J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
    [CrossRef]
  9. H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
    [CrossRef]
  10. H. Kim, S.-N. Lee, Y. Park, and T.-Y. Seong, “High-efficiency GaN-based light emitting diodes fabricated with metallic hybrid reflectors,” IEEE Electron Device Lett.29(6), 582–584 (2008).
    [CrossRef]
  11. J.-W. Jeon, W.-S. Yum, S. Oh, K.-K. Kim, and T.-Y. Seong, “Nanostructure Ag dots for improving thermal stability of Ag reflector for GaN-based light-emitting diodes,” Appl. Phys. Lett.101(2), 021115 (2012).
    [CrossRef]
  12. J. Cho, H. Kim, Y. Park, and E. Yoon, “Effects of the p-electrode reflectivity on extraction efficiency of nitride-based light emitting diodes,” Appl. Phys. Express1, 052001 (2008).
    [CrossRef]
  13. Y. Park, K.-S. Ahn, and H. Kim, “Carrier transport mechanism of Ni/Ag/Pt contacts to p-type GaN,” IEEE Trans. Electron. Dev.59(3), 680–684 (2012).
    [CrossRef]
  14. Y. Park and H. Kim, “Carrier transport and effective barrier height of low resistance metal contact to highly Mg-doped p-GaN,” Appl. Phys. Express4(8), 085701 (2011).
    [CrossRef]
  15. J. S. Kwak, O.-H. Nam, and Y. Park, “Temperature-dependent contact resistivity of the nonalloyed ohmic contacts to p-GaN,” J. Appl. Phys.95(10), 5917 (2004).
    [CrossRef]
  16. H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, Y. Park, and T.-Y. Seong, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers,” Appl. Phys. Lett.90(16), 161110 (2007).
    [CrossRef]

2012 (2)

J.-W. Jeon, W.-S. Yum, S. Oh, K.-K. Kim, and T.-Y. Seong, “Nanostructure Ag dots for improving thermal stability of Ag reflector for GaN-based light-emitting diodes,” Appl. Phys. Lett.101(2), 021115 (2012).
[CrossRef]

Y. Park, K.-S. Ahn, and H. Kim, “Carrier transport mechanism of Ni/Ag/Pt contacts to p-type GaN,” IEEE Trans. Electron. Dev.59(3), 680–684 (2012).
[CrossRef]

2011 (1)

Y. Park and H. Kim, “Carrier transport and effective barrier height of low resistance metal contact to highly Mg-doped p-GaN,” Appl. Phys. Express4(8), 085701 (2011).
[CrossRef]

2010 (1)

J. O. Song, J.-S. Ha, and T.-Y. Seong, “Ohmic-Contact technology for GaN-based light-emitting diodes: Role of p-type contact,” IEEE Trans. Electron. Dev.57(1), 42–59 (2010).
[CrossRef]

2008 (2)

H. Kim, S.-N. Lee, Y. Park, and T.-Y. Seong, “High-efficiency GaN-based light emitting diodes fabricated with metallic hybrid reflectors,” IEEE Electron Device Lett.29(6), 582–584 (2008).
[CrossRef]

J. Cho, H. Kim, Y. Park, and E. Yoon, “Effects of the p-electrode reflectivity on extraction efficiency of nitride-based light emitting diodes,” Appl. Phys. Express1, 052001 (2008).
[CrossRef]

2007 (2)

H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, Y. Park, and T.-Y. Seong, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers,” Appl. Phys. Lett.90(16), 161110 (2007).
[CrossRef]

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

2006 (1)

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

2005 (1)

J. O. Song, J. S. Kwak, Y. Park, and T.-Y. Seong, “Ohmic and degradation mechanisms of Ag contacts on p-type GaN,” Appl. Phys. Lett.86(6), 062104 (2005).
[CrossRef]

2004 (4)

J. K. Kim, T. Gessmann, H. Luo, and E. F. Schubert, “GaInN light-emitting diodes with RuO2/SiO2/Ag omni-directional reflector,” Appl. Phys. Lett.84(22), 4508 (2004).
[CrossRef]

H. W. Jang and J.-L. Lee, “Low-resistance and high-reflectance Ni/Ag/Ru/Ni/Au ohmic contact on p-type GaN,” Appl. Phys. Lett.85(19), 4421 (2004).
[CrossRef]

H. W. Jang and J.-L. Lee, “Mechanism for ohmic contact formation of Ni/Ag contacts on p-type GaN,” Appl. Phys. Lett.85(24), 5920 (2004).
[CrossRef]

J. S. Kwak, O.-H. Nam, and Y. Park, “Temperature-dependent contact resistivity of the nonalloyed ohmic contacts to p-GaN,” J. Appl. Phys.95(10), 5917 (2004).
[CrossRef]

2003 (2)

D. L. Hibbard, S. P. Jung, C. Wang, D. Ullery, Y. S. Zhao, H. P. Lee, W. So, and H. Liu, “Low resistance high reflectance contacts to p-GaN using oxidized Ni/Au and Al or Ag,” Appl. Phys. Lett.83(2), 311 (2003).
[CrossRef]

J. O. Song, D.-S. Leem, J. S. Kwak, O. H. Nam, Y. Park, and T.-Y. Seong, “Low-resistance and highly-reflective Zn–Ni solid solution/Ag ohmic contacts for flip-chip light-emitting diodes,” Appl. Phys. Lett.83(24), 4990 (2003).
[CrossRef]

Ahn, K.-S.

Y. Park, K.-S. Ahn, and H. Kim, “Carrier transport mechanism of Ni/Ag/Pt contacts to p-type GaN,” IEEE Trans. Electron. Dev.59(3), 680–684 (2012).
[CrossRef]

Baik, K. H.

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

Cho, J.

J. Cho, H. Kim, Y. Park, and E. Yoon, “Effects of the p-electrode reflectivity on extraction efficiency of nitride-based light emitting diodes,” Appl. Phys. Express1, 052001 (2008).
[CrossRef]

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, Y. Park, and T.-Y. Seong, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers,” Appl. Phys. Lett.90(16), 161110 (2007).
[CrossRef]

Choi, D.

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

Gessmann, T.

J. K. Kim, T. Gessmann, H. Luo, and E. F. Schubert, “GaInN light-emitting diodes with RuO2/SiO2/Ag omni-directional reflector,” Appl. Phys. Lett.84(22), 4508 (2004).
[CrossRef]

Ha, G.-Y.

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

Ha, J.-S.

J. O. Song, J.-S. Ha, and T.-Y. Seong, “Ohmic-Contact technology for GaN-based light-emitting diodes: Role of p-type contact,” IEEE Trans. Electron. Dev.57(1), 42–59 (2010).
[CrossRef]

Hibbard, D. L.

D. L. Hibbard, S. P. Jung, C. Wang, D. Ullery, Y. S. Zhao, H. P. Lee, W. So, and H. Liu, “Low resistance high reflectance contacts to p-GaN using oxidized Ni/Au and Al or Ag,” Appl. Phys. Lett.83(2), 311 (2003).
[CrossRef]

Jang, H. W.

H. W. Jang and J.-L. Lee, “Low-resistance and high-reflectance Ni/Ag/Ru/Ni/Au ohmic contact on p-type GaN,” Appl. Phys. Lett.85(19), 4421 (2004).
[CrossRef]

H. W. Jang and J.-L. Lee, “Mechanism for ohmic contact formation of Ni/Ag contacts on p-type GaN,” Appl. Phys. Lett.85(24), 5920 (2004).
[CrossRef]

Jeon, J.-W.

J.-W. Jeon, W.-S. Yum, S. Oh, K.-K. Kim, and T.-Y. Seong, “Nanostructure Ag dots for improving thermal stability of Ag reflector for GaN-based light-emitting diodes,” Appl. Phys. Lett.101(2), 021115 (2012).
[CrossRef]

Jung, S. P.

D. L. Hibbard, S. P. Jung, C. Wang, D. Ullery, Y. S. Zhao, H. P. Lee, W. So, and H. Liu, “Low resistance high reflectance contacts to p-GaN using oxidized Ni/Au and Al or Ag,” Appl. Phys. Lett.83(2), 311 (2003).
[CrossRef]

Kim, H.

Y. Park, K.-S. Ahn, and H. Kim, “Carrier transport mechanism of Ni/Ag/Pt contacts to p-type GaN,” IEEE Trans. Electron. Dev.59(3), 680–684 (2012).
[CrossRef]

Y. Park and H. Kim, “Carrier transport and effective barrier height of low resistance metal contact to highly Mg-doped p-GaN,” Appl. Phys. Express4(8), 085701 (2011).
[CrossRef]

J. Cho, H. Kim, Y. Park, and E. Yoon, “Effects of the p-electrode reflectivity on extraction efficiency of nitride-based light emitting diodes,” Appl. Phys. Express1, 052001 (2008).
[CrossRef]

H. Kim, S.-N. Lee, Y. Park, and T.-Y. Seong, “High-efficiency GaN-based light emitting diodes fabricated with metallic hybrid reflectors,” IEEE Electron Device Lett.29(6), 582–584 (2008).
[CrossRef]

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, Y. Park, and T.-Y. Seong, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers,” Appl. Phys. Lett.90(16), 161110 (2007).
[CrossRef]

H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, Y. Park, and T.-Y. Seong, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers,” Appl. Phys. Lett.90(16), 161110 (2007).
[CrossRef]

Kim, J. K.

J. K. Kim, T. Gessmann, H. Luo, and E. F. Schubert, “GaInN light-emitting diodes with RuO2/SiO2/Ag omni-directional reflector,” Appl. Phys. Lett.84(22), 4508 (2004).
[CrossRef]

Kim, J.-Y.

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

Kim, K.-K.

J.-W. Jeon, W.-S. Yum, S. Oh, K.-K. Kim, and T.-Y. Seong, “Nanostructure Ag dots for improving thermal stability of Ag reflector for GaN-based light-emitting diodes,” Appl. Phys. Lett.101(2), 021115 (2012).
[CrossRef]

Kim, M.-H.

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

Kwak, J. S.

J. O. Song, J. S. Kwak, Y. Park, and T.-Y. Seong, “Ohmic and degradation mechanisms of Ag contacts on p-type GaN,” Appl. Phys. Lett.86(6), 062104 (2005).
[CrossRef]

J. S. Kwak, O.-H. Nam, and Y. Park, “Temperature-dependent contact resistivity of the nonalloyed ohmic contacts to p-GaN,” J. Appl. Phys.95(10), 5917 (2004).
[CrossRef]

J. O. Song, D.-S. Leem, J. S. Kwak, O. H. Nam, Y. Park, and T.-Y. Seong, “Low-resistance and highly-reflective Zn–Ni solid solution/Ag ohmic contacts for flip-chip light-emitting diodes,” Appl. Phys. Lett.83(24), 4990 (2003).
[CrossRef]

Kwon, M.-K.

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

Lee, H. P.

D. L. Hibbard, S. P. Jung, C. Wang, D. Ullery, Y. S. Zhao, H. P. Lee, W. So, and H. Liu, “Low resistance high reflectance contacts to p-GaN using oxidized Ni/Au and Al or Ag,” Appl. Phys. Lett.83(2), 311 (2003).
[CrossRef]

Lee, J. W.

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, Y. Park, and T.-Y. Seong, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers,” Appl. Phys. Lett.90(16), 161110 (2007).
[CrossRef]

Lee, J.-L.

H. W. Jang and J.-L. Lee, “Mechanism for ohmic contact formation of Ni/Ag contacts on p-type GaN,” Appl. Phys. Lett.85(24), 5920 (2004).
[CrossRef]

H. W. Jang and J.-L. Lee, “Low-resistance and high-reflectance Ni/Ag/Ru/Ni/Au ohmic contact on p-type GaN,” Appl. Phys. Lett.85(19), 4421 (2004).
[CrossRef]

Lee, S.-N.

H. Kim, S.-N. Lee, Y. Park, and T.-Y. Seong, “High-efficiency GaN-based light emitting diodes fabricated with metallic hybrid reflectors,” IEEE Electron Device Lett.29(6), 582–584 (2008).
[CrossRef]

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

Leem, D.-S.

J. O. Song, D.-S. Leem, J. S. Kwak, O. H. Nam, Y. Park, and T.-Y. Seong, “Low-resistance and highly-reflective Zn–Ni solid solution/Ag ohmic contacts for flip-chip light-emitting diodes,” Appl. Phys. Lett.83(24), 4990 (2003).
[CrossRef]

Lim, J.-H.

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

Liu, H.

D. L. Hibbard, S. P. Jung, C. Wang, D. Ullery, Y. S. Zhao, H. P. Lee, W. So, and H. Liu, “Low resistance high reflectance contacts to p-GaN using oxidized Ni/Au and Al or Ag,” Appl. Phys. Lett.83(2), 311 (2003).
[CrossRef]

Luo, H.

J. K. Kim, T. Gessmann, H. Luo, and E. F. Schubert, “GaInN light-emitting diodes with RuO2/SiO2/Ag omni-directional reflector,” Appl. Phys. Lett.84(22), 4508 (2004).
[CrossRef]

Min, K.

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

Na, S.-I.

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

Nam, O. H.

J. O. Song, D.-S. Leem, J. S. Kwak, O. H. Nam, Y. Park, and T.-Y. Seong, “Low-resistance and highly-reflective Zn–Ni solid solution/Ag ohmic contacts for flip-chip light-emitting diodes,” Appl. Phys. Lett.83(24), 4990 (2003).
[CrossRef]

Nam, O.-H.

J. S. Kwak, O.-H. Nam, and Y. Park, “Temperature-dependent contact resistivity of the nonalloyed ohmic contacts to p-GaN,” J. Appl. Phys.95(10), 5917 (2004).
[CrossRef]

Oh, S.

J.-W. Jeon, W.-S. Yum, S. Oh, K.-K. Kim, and T.-Y. Seong, “Nanostructure Ag dots for improving thermal stability of Ag reflector for GaN-based light-emitting diodes,” Appl. Phys. Lett.101(2), 021115 (2012).
[CrossRef]

Park, I.-K.

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

Park, S.-J.

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

Park, Y.

Y. Park, K.-S. Ahn, and H. Kim, “Carrier transport mechanism of Ni/Ag/Pt contacts to p-type GaN,” IEEE Trans. Electron. Dev.59(3), 680–684 (2012).
[CrossRef]

Y. Park and H. Kim, “Carrier transport and effective barrier height of low resistance metal contact to highly Mg-doped p-GaN,” Appl. Phys. Express4(8), 085701 (2011).
[CrossRef]

J. Cho, H. Kim, Y. Park, and E. Yoon, “Effects of the p-electrode reflectivity on extraction efficiency of nitride-based light emitting diodes,” Appl. Phys. Express1, 052001 (2008).
[CrossRef]

H. Kim, S.-N. Lee, Y. Park, and T.-Y. Seong, “High-efficiency GaN-based light emitting diodes fabricated with metallic hybrid reflectors,” IEEE Electron Device Lett.29(6), 582–584 (2008).
[CrossRef]

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, Y. Park, and T.-Y. Seong, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers,” Appl. Phys. Lett.90(16), 161110 (2007).
[CrossRef]

J. O. Song, J. S. Kwak, Y. Park, and T.-Y. Seong, “Ohmic and degradation mechanisms of Ag contacts on p-type GaN,” Appl. Phys. Lett.86(6), 062104 (2005).
[CrossRef]

J. S. Kwak, O.-H. Nam, and Y. Park, “Temperature-dependent contact resistivity of the nonalloyed ohmic contacts to p-GaN,” J. Appl. Phys.95(10), 5917 (2004).
[CrossRef]

J. O. Song, D.-S. Leem, J. S. Kwak, O. H. Nam, Y. Park, and T.-Y. Seong, “Low-resistance and highly-reflective Zn–Ni solid solution/Ag ohmic contacts for flip-chip light-emitting diodes,” Appl. Phys. Lett.83(24), 4990 (2003).
[CrossRef]

Schubert, E. F.

J. K. Kim, T. Gessmann, H. Luo, and E. F. Schubert, “GaInN light-emitting diodes with RuO2/SiO2/Ag omni-directional reflector,” Appl. Phys. Lett.84(22), 4508 (2004).
[CrossRef]

Seong, T.-Y.

J.-W. Jeon, W.-S. Yum, S. Oh, K.-K. Kim, and T.-Y. Seong, “Nanostructure Ag dots for improving thermal stability of Ag reflector for GaN-based light-emitting diodes,” Appl. Phys. Lett.101(2), 021115 (2012).
[CrossRef]

J. O. Song, J.-S. Ha, and T.-Y. Seong, “Ohmic-Contact technology for GaN-based light-emitting diodes: Role of p-type contact,” IEEE Trans. Electron. Dev.57(1), 42–59 (2010).
[CrossRef]

H. Kim, S.-N. Lee, Y. Park, and T.-Y. Seong, “High-efficiency GaN-based light emitting diodes fabricated with metallic hybrid reflectors,” IEEE Electron Device Lett.29(6), 582–584 (2008).
[CrossRef]

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, Y. Park, and T.-Y. Seong, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers,” Appl. Phys. Lett.90(16), 161110 (2007).
[CrossRef]

J. O. Song, J. S. Kwak, Y. Park, and T.-Y. Seong, “Ohmic and degradation mechanisms of Ag contacts on p-type GaN,” Appl. Phys. Lett.86(6), 062104 (2005).
[CrossRef]

J. O. Song, D.-S. Leem, J. S. Kwak, O. H. Nam, Y. Park, and T.-Y. Seong, “Low-resistance and highly-reflective Zn–Ni solid solution/Ag ohmic contacts for flip-chip light-emitting diodes,” Appl. Phys. Lett.83(24), 4990 (2003).
[CrossRef]

So, W.

D. L. Hibbard, S. P. Jung, C. Wang, D. Ullery, Y. S. Zhao, H. P. Lee, W. So, and H. Liu, “Low resistance high reflectance contacts to p-GaN using oxidized Ni/Au and Al or Ag,” Appl. Phys. Lett.83(2), 311 (2003).
[CrossRef]

Sone, C.

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, Y. Park, and T.-Y. Seong, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers,” Appl. Phys. Lett.90(16), 161110 (2007).
[CrossRef]

Song, J. O.

J. O. Song, J.-S. Ha, and T.-Y. Seong, “Ohmic-Contact technology for GaN-based light-emitting diodes: Role of p-type contact,” IEEE Trans. Electron. Dev.57(1), 42–59 (2010).
[CrossRef]

J. O. Song, J. S. Kwak, Y. Park, and T.-Y. Seong, “Ohmic and degradation mechanisms of Ag contacts on p-type GaN,” Appl. Phys. Lett.86(6), 062104 (2005).
[CrossRef]

J. O. Song, D.-S. Leem, J. S. Kwak, O. H. Nam, Y. Park, and T.-Y. Seong, “Low-resistance and highly-reflective Zn–Ni solid solution/Ag ohmic contacts for flip-chip light-emitting diodes,” Appl. Phys. Lett.83(24), 4990 (2003).
[CrossRef]

Ullery, D.

D. L. Hibbard, S. P. Jung, C. Wang, D. Ullery, Y. S. Zhao, H. P. Lee, W. So, and H. Liu, “Low resistance high reflectance contacts to p-GaN using oxidized Ni/Au and Al or Ag,” Appl. Phys. Lett.83(2), 311 (2003).
[CrossRef]

Wang, C.

D. L. Hibbard, S. P. Jung, C. Wang, D. Ullery, Y. S. Zhao, H. P. Lee, W. So, and H. Liu, “Low resistance high reflectance contacts to p-GaN using oxidized Ni/Au and Al or Ag,” Appl. Phys. Lett.83(2), 311 (2003).
[CrossRef]

Yoon, E.

J. Cho, H. Kim, Y. Park, and E. Yoon, “Effects of the p-electrode reflectivity on extraction efficiency of nitride-based light emitting diodes,” Appl. Phys. Express1, 052001 (2008).
[CrossRef]

Yoon, S.

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, Y. Park, and T.-Y. Seong, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers,” Appl. Phys. Lett.90(16), 161110 (2007).
[CrossRef]

Yum, W.-S.

J.-W. Jeon, W.-S. Yum, S. Oh, K.-K. Kim, and T.-Y. Seong, “Nanostructure Ag dots for improving thermal stability of Ag reflector for GaN-based light-emitting diodes,” Appl. Phys. Lett.101(2), 021115 (2012).
[CrossRef]

Zhao, Y. S.

D. L. Hibbard, S. P. Jung, C. Wang, D. Ullery, Y. S. Zhao, H. P. Lee, W. So, and H. Liu, “Low resistance high reflectance contacts to p-GaN using oxidized Ni/Au and Al or Ag,” Appl. Phys. Lett.83(2), 311 (2003).
[CrossRef]

Appl. Phys. Express (2)

J. Cho, H. Kim, Y. Park, and E. Yoon, “Effects of the p-electrode reflectivity on extraction efficiency of nitride-based light emitting diodes,” Appl. Phys. Express1, 052001 (2008).
[CrossRef]

Y. Park and H. Kim, “Carrier transport and effective barrier height of low resistance metal contact to highly Mg-doped p-GaN,” Appl. Phys. Express4(8), 085701 (2011).
[CrossRef]

Appl. Phys. Lett. (9)

J.-W. Jeon, W.-S. Yum, S. Oh, K.-K. Kim, and T.-Y. Seong, “Nanostructure Ag dots for improving thermal stability of Ag reflector for GaN-based light-emitting diodes,” Appl. Phys. Lett.101(2), 021115 (2012).
[CrossRef]

H. Kim, J. Cho, J. W. Lee, S. Yoon, H. Kim, C. Sone, Y. Park, and T.-Y. Seong, “Enhanced light extraction of GaN-based light-emitting diodes by using textured n-type GaN layers,” Appl. Phys. Lett.90(16), 161110 (2007).
[CrossRef]

D. L. Hibbard, S. P. Jung, C. Wang, D. Ullery, Y. S. Zhao, H. P. Lee, W. So, and H. Liu, “Low resistance high reflectance contacts to p-GaN using oxidized Ni/Au and Al or Ag,” Appl. Phys. Lett.83(2), 311 (2003).
[CrossRef]

J. O. Song, D.-S. Leem, J. S. Kwak, O. H. Nam, Y. Park, and T.-Y. Seong, “Low-resistance and highly-reflective Zn–Ni solid solution/Ag ohmic contacts for flip-chip light-emitting diodes,” Appl. Phys. Lett.83(24), 4990 (2003).
[CrossRef]

J. K. Kim, T. Gessmann, H. Luo, and E. F. Schubert, “GaInN light-emitting diodes with RuO2/SiO2/Ag omni-directional reflector,” Appl. Phys. Lett.84(22), 4508 (2004).
[CrossRef]

H. W. Jang and J.-L. Lee, “Low-resistance and high-reflectance Ni/Ag/Ru/Ni/Au ohmic contact on p-type GaN,” Appl. Phys. Lett.85(19), 4421 (2004).
[CrossRef]

H. W. Jang and J.-L. Lee, “Mechanism for ohmic contact formation of Ni/Ag contacts on p-type GaN,” Appl. Phys. Lett.85(24), 5920 (2004).
[CrossRef]

J. O. Song, J. S. Kwak, Y. Park, and T.-Y. Seong, “Ohmic and degradation mechanisms of Ag contacts on p-type GaN,” Appl. Phys. Lett.86(6), 062104 (2005).
[CrossRef]

J.-Y. Kim, S.-I. Na, G.-Y. Ha, M.-K. Kwon, I.-K. Park, J.-H. Lim, S.-J. Park, M.-H. Kim, D. Choi, and K. Min, “Thermally stable and highly reflective AgAl alloy for enhancing light extraction efficiency in GaN light-emitting diodes,” Appl. Phys. Lett.88(4), 043507 (2006).
[CrossRef]

IEEE Electron Device Lett. (1)

H. Kim, S.-N. Lee, Y. Park, and T.-Y. Seong, “High-efficiency GaN-based light emitting diodes fabricated with metallic hybrid reflectors,” IEEE Electron Device Lett.29(6), 582–584 (2008).
[CrossRef]

IEEE Photon. Technol. Lett. (1)

H. Kim, K. H. Baik, J. Cho, J. W. Lee, S. Yoon, H. Kim, S.-N. Lee, C. Sone, Y. Park, and T.-Y. Seong, “High-reflectance and thermally stable AgCu Alloy p-type reflectors for GaN-based LEDs,” IEEE Photon. Technol. Lett.19(5), 336–338 (2007).
[CrossRef]

IEEE Trans. Electron. Dev. (2)

J. O. Song, J.-S. Ha, and T.-Y. Seong, “Ohmic-Contact technology for GaN-based light-emitting diodes: Role of p-type contact,” IEEE Trans. Electron. Dev.57(1), 42–59 (2010).
[CrossRef]

Y. Park, K.-S. Ahn, and H. Kim, “Carrier transport mechanism of Ni/Ag/Pt contacts to p-type GaN,” IEEE Trans. Electron. Dev.59(3), 680–684 (2012).
[CrossRef]

J. Appl. Phys. (1)

J. S. Kwak, O.-H. Nam, and Y. Park, “Temperature-dependent contact resistivity of the nonalloyed ohmic contacts to p-GaN,” J. Appl. Phys.95(10), 5917 (2004).
[CrossRef]

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Figures (6)

Fig. 1
Fig. 1

Electrical and optical characteristics of Ag contact to n-GaN as a function of annealing temperature (a) IV characteristics. (b) ρsc and Rop vs. annealing conditions. The inset of Fig. 1(a) shows TLM patterns.

Fig. 2
Fig. 2

SIMS depth profiles of Ag/n-GaN interface before and after thermal annealing performed at 500 °C for 1 min in N2 and O2 ambient.

Fig. 3
Fig. 3

Optical microscopic top-views of as-deposited and thermally annealed (500 °C in O2 and N2 ambient) Ag surfaces.

Fig. 4
Fig. 4

IV curves of Ag contacts to p-GaN obtained after annealing at 500 °C for 1 min in N2 and O2 ambient.

Fig. 5
Fig. 5

Electrical and optical characteristics of LEDs (a) I-V curves of fabricated Ag LEDs and reference LEDs. (b) Optical output power of LEDs as a function of injection current. The inset of Fig. 5(b) shows electroluminescent LED images taken by optical microscopy (at 1 mA).

Fig. 6
Fig. 6

Calculated extraction efficiency of LEDs fabricated with different optical reflectivity of n- and p-contacts. The inset shows 3-dimensional LEDs chips designed for simulation.

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