Abstract

Analysis of transverse magnetic (TM) mode light extraction efficiency enhancement for AlGaN quantum wells (QWs) based deep ultraviolet (UV) light-emitting diodes (LEDs) with III-nitride micro-hemisphere and micro-dome structures on the p-type layer are studied and compared to that of the conventional deep-UV LEDs with flat surface. The transverse electric (TE) and TM components of the spontaneous emission of AlGaN QWs with AlN barriers were calculated by using a self-consistent 6-band k∙p method, which shows the TM component overtakes the TE component and becomes the dominant contribution of the spontaneous emission when the Al-content of the AlGaN QWs is larger than 0.66. The TM mode light extraction efficiency of the deep-UV LEDs emitting at 250 nm with AlGaN micro-domes as compared to the conventional LEDs with flat surface is calculated based on three dimensional finite difference time domain (3D-FDTD) method. The effects of the III-nitride micro-dome diameter and height as well as the p-type layer thickness on the light extraction efficiency were comprehensively studied. The results indicate optimized light extraction efficiency enhancement (>7.3 times) of the dominant TM polarized spontaneous emission for deep-UV LEDs with III-nitride micro-domes.

©2012 Optical Society of America

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    [Crossref]
  2. M. Asif Khan, “AlGaN multiple quantum well based deep UV LEDs and their applications,” Phys. Status Solidi A 203(7), 1764–1770 (2006).
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  3. A. A. Allerman, M. H. Crawford, A. J. Fischer, K. H. A. Bogart, S. R. Lee, D. M. Follstaedt, P. P. Provencio, and D. D. Koleske, “Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys,” J. Cryst. Growth 272(1-4), 227–241 (2004).
    [Crossref]
  4. H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A 206(6), 1176–1182 (2009).
    [Crossref]
  5. S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, “High-brightness InGaN blue, green and yellow light-emitting diodes with quantum well structures,” Jpn. J. Appl. Phys. 34(Part 2, No. 7A), L797–L799 (1995).
    [Crossref]
  6. Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
    [Crossref]
  7. J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
    [Crossref]
  8. T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
    [Crossref]
  9. H. Zhao, G. Liu, J. Zhang, J. D. Poplawsky, V. Dierolf, and N. Tansu, “Approaches for high internal quantum efficiency green InGaN light-emitting diodes with large overlap quantum wells,” Opt. Express 19(S4Suppl 4), A991–A1007 (2011).
    [Crossref] [PubMed]
  10. H. Zhao, R. A. Arif, and N. Tansu, “Design analysis of staggered InGaN quantum wells light-emitting diodes at 500–540 nm,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1104–1114 (2009).
    [Crossref]
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    [Crossref]
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    [Crossref]
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    [Crossref]
  15. Y.-K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, H. Zhao, J. F. Gilchrist, and N. Tansu, “Optimization of light extraction efficiency of III-Nitride light emitting diodes with self-assembled colloidal-based microlenses,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1218–1225 (2009).
    [Crossref]
  16. P. Kumnorkaew, Y. K. Ee, N. Tansu, and J. F. Gilchrist, “Investigation of the deposition of microsphere monolayers for fabrication of microlens arrays,” Langmuir 24(21), 12150–12157 (2008).
    [Crossref] [PubMed]
  17. X.-H. Li, R. Song, Y.-K. Ee, P. Kumnorkaew, J. F. Gilchrist, and N. Tansu, “Light extraction efficiency and radiation patterns of III-nitride light-emitting diodes with colloidal microlens arrays with various aspect ratios,” IEEE Photon. J. 3(3), 489–499 (2011).
    [Crossref]
  18. Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S. Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).
  19. P. Zhao and H. Zhao, “Analysis of light extraction efficiency enhancement for thin-film-flip-chip InGaN quantum wells light-emitting diodes with GaN micro-domes,” Opt. Express 20(S5), A765–A776 (2012).
    [Crossref]
  20. W. N. Ng, C. H. Leung, P. T. Lai, and H. W. Choi, “Nanostructuring GaN using microsphere lithography,” J. Vac. Sci. Technol. B 26(1), 76–79 (2008).
    [Crossref]
  21. W. Y. Fu, K.-K. Wong, and H. W. Choi, “Close-packed hemiellipsoid arrays: a photonic band gap structure patterned by nanosphere lithography,” Appl. Phys. Lett. 95(13), 133125 (2009).
    [Crossref]
  22. Lumerical FDTD Solution.
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  24. J. Zhang, H. Zhao, and N. Tansu, “Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers,” Appl. Phys. Lett. 97(11), 111105 (2010).
    [Crossref]
  25. J. Zhang, H. Zhao, and N. Tansu, “Large optical gain AlGaN-Delta-GaN quantum wells laser active regions in mid- and deep-ultraviolet spectral regimes,” Appl. Phys. Lett. 98(17), 171111 (2011).
    [Crossref]
  26. Y. Taniyasu and M. Kasu, “Polarization property of deep-ultraviolet light emission from C-plane AlN/GaN short-period superlattices,” Appl. Phys. Lett. 99(25), 251112 (2011).
    [Crossref]
  27. H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Self-consistent analysis of strain-compensated InGaN-AlGaN quantum wells for lasers and light emitting diodes,” IEEE J. Quantum Electron. 45(1), 66–78 (2009).
    [Crossref]
  28. H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Optical gain analysis of strain-compensated InGaN–AlGaN quantum well active regions for lasers emitting at 420-500 nm,” Opt. Quantum Electron. 40(5-6), 301–306 (2008).
    [Crossref]
  29. S. L. Chuang, “Optical gain of strained wurtzite GaN quantum-well lasers,” IEEE J. Quantum Electron. 32(10), 1791–1800 (1996).
    [Crossref]
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  31. I. Vurgaftman and J. R. Meyer, “Band parameters for nitrogen-containing semiconductors,” J. Appl. Phys. 94(6), 3675–3696 (2003).
    [Crossref]
  32. A. Khan, K. Balakrishnan, and T. Katona, “Ultraviolet light-emitting diodes based on group three nitrides,” Nat. Photonics 2(2), 77–84 (2008).
    [Crossref]
  33. M. Asif Khan, M. Shatalov, H. P. Maruska, H. M. Wang, and E. Kuokstis, “III–nitride UV devices,” Jpn. J. Appl. Phys. 44(10), 7191–7206 (2005).
    [Crossref]

2012 (1)

2011 (4)

H. Zhao, G. Liu, J. Zhang, J. D. Poplawsky, V. Dierolf, and N. Tansu, “Approaches for high internal quantum efficiency green InGaN light-emitting diodes with large overlap quantum wells,” Opt. Express 19(S4Suppl 4), A991–A1007 (2011).
[Crossref] [PubMed]

J. Zhang, H. Zhao, and N. Tansu, “Large optical gain AlGaN-Delta-GaN quantum wells laser active regions in mid- and deep-ultraviolet spectral regimes,” Appl. Phys. Lett. 98(17), 171111 (2011).
[Crossref]

Y. Taniyasu and M. Kasu, “Polarization property of deep-ultraviolet light emission from C-plane AlN/GaN short-period superlattices,” Appl. Phys. Lett. 99(25), 251112 (2011).
[Crossref]

X.-H. Li, R. Song, Y.-K. Ee, P. Kumnorkaew, J. F. Gilchrist, and N. Tansu, “Light extraction efficiency and radiation patterns of III-nitride light-emitting diodes with colloidal microlens arrays with various aspect ratios,” IEEE Photon. J. 3(3), 489–499 (2011).
[Crossref]

2010 (1)

J. Zhang, H. Zhao, and N. Tansu, “Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers,” Appl. Phys. Lett. 97(11), 111105 (2010).
[Crossref]

2009 (7)

W. Y. Fu, K.-K. Wong, and H. W. Choi, “Close-packed hemiellipsoid arrays: a photonic band gap structure patterned by nanosphere lithography,” Appl. Phys. Lett. 95(13), 133125 (2009).
[Crossref]

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Self-consistent analysis of strain-compensated InGaN-AlGaN quantum wells for lasers and light emitting diodes,” IEEE J. Quantum Electron. 45(1), 66–78 (2009).
[Crossref]

J. J. Wierer, A. David, and M. M. Megens, “III-nitride photoniccrystal light-emitting diodes with high extraction efficiency,” Nat. Photonics 3(3), 163–169 (2009).
[Crossref]

Y.-K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, H. Zhao, J. F. Gilchrist, and N. Tansu, “Optimization of light extraction efficiency of III-Nitride light emitting diodes with self-assembled colloidal-based microlenses,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1218–1225 (2009).
[Crossref]

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A 206(6), 1176–1182 (2009).
[Crossref]

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

H. Zhao, R. A. Arif, and N. Tansu, “Design analysis of staggered InGaN quantum wells light-emitting diodes at 500–540 nm,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1104–1114 (2009).
[Crossref]

2008 (5)

J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
[Crossref]

P. Kumnorkaew, Y. K. Ee, N. Tansu, and J. F. Gilchrist, “Investigation of the deposition of microsphere monolayers for fabrication of microlens arrays,” Langmuir 24(21), 12150–12157 (2008).
[Crossref] [PubMed]

W. N. Ng, C. H. Leung, P. T. Lai, and H. W. Choi, “Nanostructuring GaN using microsphere lithography,” J. Vac. Sci. Technol. B 26(1), 76–79 (2008).
[Crossref]

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Optical gain analysis of strain-compensated InGaN–AlGaN quantum well active regions for lasers emitting at 420-500 nm,” Opt. Quantum Electron. 40(5-6), 301–306 (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 (3)

Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S. Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Y.-K. Ee, R. A. Arif, N. Tansu, P. Kumnorkaew, and J. F. Gilchrist, “Enhancement of light extraction efficiency of InGaN quantum wells light emitting diodes using SiO2/polystyrene microlens arrays,” Appl. Phys. Lett. 91(22), 221107 (2007).
[Crossref]

H. Hirayama, T. Yatabe, N. Noguchi, T. Ohashi, and N. Kamata, “231–261 nm AlGaN deep-ultraviolet light-emitting diodes fabricated on AlN multilayer buffers grown by ammonia pulse-flow method on sapphire,” Appl. Phys. Lett. 91(7), 071901 (2007).
[Crossref]

2006 (2)

M. Asif Khan, “AlGaN multiple quantum well based deep UV LEDs and their applications,” Phys. Status Solidi A 203(7), 1764–1770 (2006).
[Crossref]

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[Crossref]

2005 (1)

M. Asif Khan, M. Shatalov, H. P. Maruska, H. M. Wang, and E. Kuokstis, “III–nitride UV devices,” Jpn. J. Appl. Phys. 44(10), 7191–7206 (2005).
[Crossref]

2004 (2)

A. A. Allerman, M. H. Crawford, A. J. Fischer, K. H. A. Bogart, S. R. Lee, D. M. Follstaedt, P. P. Provencio, and D. D. Koleske, “Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys,” J. Cryst. Growth 272(1-4), 227–241 (2004).
[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]

2003 (2)

C. Huh, K. S. Lee, E. J. Kang, and S. J. Park, “Improved light-output and electrical performance of InGaN-based light-emitting diode by microroughening of the p-GaN surface,” J. Appl. Phys. 93(11), 9383–9385 (2003).
[Crossref]

I. Vurgaftman and J. R. Meyer, “Band parameters for nitrogen-containing semiconductors,” J. Appl. Phys. 94(6), 3675–3696 (2003).
[Crossref]

1996 (1)

S. L. Chuang, “Optical gain of strained wurtzite GaN quantum-well lasers,” IEEE J. Quantum Electron. 32(10), 1791–1800 (1996).
[Crossref]

1995 (1)

S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, “High-brightness InGaN blue, green and yellow light-emitting diodes with quantum well structures,” Jpn. J. Appl. Phys. 34(Part 2, No. 7A), L797–L799 (1995).
[Crossref]

Allerman, A. A.

A. A. Allerman, M. H. Crawford, A. J. Fischer, K. H. A. Bogart, S. R. Lee, D. M. Follstaedt, P. P. Provencio, and D. D. Koleske, “Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys,” J. Cryst. Growth 272(1-4), 227–241 (2004).
[Crossref]

Arif, R. A.

H. Zhao, R. A. Arif, and N. Tansu, “Design analysis of staggered InGaN quantum wells light-emitting diodes at 500–540 nm,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1104–1114 (2009).
[Crossref]

Y.-K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, H. Zhao, J. F. Gilchrist, and N. Tansu, “Optimization of light extraction efficiency of III-Nitride light emitting diodes with self-assembled colloidal-based microlenses,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1218–1225 (2009).
[Crossref]

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Self-consistent analysis of strain-compensated InGaN-AlGaN quantum wells for lasers and light emitting diodes,” IEEE J. Quantum Electron. 45(1), 66–78 (2009).
[Crossref]

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Optical gain analysis of strain-compensated InGaN–AlGaN quantum well active regions for lasers emitting at 420-500 nm,” Opt. Quantum Electron. 40(5-6), 301–306 (2008).
[Crossref]

Y.-K. Ee, R. A. Arif, N. Tansu, P. Kumnorkaew, and J. F. Gilchrist, “Enhancement of light extraction efficiency of InGaN quantum wells light emitting diodes using SiO2/polystyrene microlens arrays,” Appl. Phys. Lett. 91(22), 221107 (2007).
[Crossref]

Asif Khan, M.

M. Asif Khan, “AlGaN multiple quantum well based deep UV LEDs and their applications,” Phys. Status Solidi A 203(7), 1764–1770 (2006).
[Crossref]

M. Asif Khan, M. Shatalov, H. P. Maruska, H. M. Wang, and E. Kuokstis, “III–nitride UV devices,” Jpn. J. Appl. Phys. 44(10), 7191–7206 (2005).
[Crossref]

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]

Banas, M. A.

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

Bogart, K. H. A.

A. A. Allerman, M. H. Crawford, A. J. Fischer, K. H. A. Bogart, S. R. Lee, D. M. Follstaedt, P. P. Provencio, and D. D. Koleske, “Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys,” J. Cryst. Growth 272(1-4), 227–241 (2004).
[Crossref]

Chakraborty, A.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[Crossref]

Chen, M.

Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S. Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Chichibu, S. F.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[Crossref]

Choi, H. W.

W. Y. Fu, K.-K. Wong, and H. W. Choi, “Close-packed hemiellipsoid arrays: a photonic band gap structure patterned by nanosphere lithography,” Appl. Phys. Lett. 95(13), 133125 (2009).
[Crossref]

W. N. Ng, C. H. Leung, P. T. Lai, and H. W. Choi, “Nanostructuring GaN using microsphere lithography,” J. Vac. Sci. Technol. B 26(1), 76–79 (2008).
[Crossref]

Chuang, S. L.

S. L. Chuang, “Optical gain of strained wurtzite GaN quantum-well lasers,” IEEE J. Quantum Electron. 32(10), 1791–1800 (1996).
[Crossref]

Crawford, M. H.

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

A. A. Allerman, M. H. Crawford, A. J. Fischer, K. H. A. Bogart, S. R. Lee, D. M. Follstaedt, P. P. Provencio, and D. D. Koleske, “Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys,” J. Cryst. Growth 272(1-4), 227–241 (2004).
[Crossref]

Dai, Q.

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

David, A.

J. J. Wierer, A. David, and M. M. Megens, “III-nitride photoniccrystal light-emitting diodes with high extraction efficiency,” Nat. Photonics 3(3), 163–169 (2009).
[Crossref]

DenBaars, S. P.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[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]

Dierolf, V.

Dupuis, R. D.

J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
[Crossref]

Ee, Y. K.

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Self-consistent analysis of strain-compensated InGaN-AlGaN quantum wells for lasers and light emitting diodes,” IEEE J. Quantum Electron. 45(1), 66–78 (2009).
[Crossref]

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Optical gain analysis of strain-compensated InGaN–AlGaN quantum well active regions for lasers emitting at 420-500 nm,” Opt. Quantum Electron. 40(5-6), 301–306 (2008).
[Crossref]

P. Kumnorkaew, Y. K. Ee, N. Tansu, and J. F. Gilchrist, “Investigation of the deposition of microsphere monolayers for fabrication of microlens arrays,” Langmuir 24(21), 12150–12157 (2008).
[Crossref] [PubMed]

Ee, Y.-K.

X.-H. Li, R. Song, Y.-K. Ee, P. Kumnorkaew, J. F. Gilchrist, and N. Tansu, “Light extraction efficiency and radiation patterns of III-nitride light-emitting diodes with colloidal microlens arrays with various aspect ratios,” IEEE Photon. J. 3(3), 489–499 (2011).
[Crossref]

Y.-K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, H. Zhao, J. F. Gilchrist, and N. Tansu, “Optimization of light extraction efficiency of III-Nitride light emitting diodes with self-assembled colloidal-based microlenses,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1218–1225 (2009).
[Crossref]

Y.-K. Ee, R. A. Arif, N. Tansu, P. Kumnorkaew, and J. F. Gilchrist, “Enhancement of light extraction efficiency of InGaN quantum wells light emitting diodes using SiO2/polystyrene microlens arrays,” Appl. Phys. Lett. 91(22), 221107 (2007).
[Crossref]

Fischer, A. J.

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

A. A. Allerman, M. H. Crawford, A. J. Fischer, K. H. A. Bogart, S. R. Lee, D. M. Follstaedt, P. P. Provencio, and D. D. Koleske, “Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys,” J. Cryst. Growth 272(1-4), 227–241 (2004).
[Crossref]

Fischer, A. M.

J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
[Crossref]

Follstaedt, D. M.

A. A. Allerman, M. H. Crawford, A. J. Fischer, K. H. A. Bogart, S. R. Lee, D. M. Follstaedt, P. P. Provencio, and D. D. Koleske, “Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys,” J. Cryst. Growth 272(1-4), 227–241 (2004).
[Crossref]

Fu, W. Y.

W. Y. Fu, K.-K. Wong, and H. W. Choi, “Close-packed hemiellipsoid arrays: a photonic band gap structure patterned by nanosphere lithography,” Appl. Phys. Lett. 95(13), 133125 (2009).
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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]

Fujikawa, S.

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A 206(6), 1176–1182 (2009).
[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]

Gilchrist, J. F.

X.-H. Li, R. Song, Y.-K. Ee, P. Kumnorkaew, J. F. Gilchrist, and N. Tansu, “Light extraction efficiency and radiation patterns of III-nitride light-emitting diodes with colloidal microlens arrays with various aspect ratios,” IEEE Photon. J. 3(3), 489–499 (2011).
[Crossref]

Y.-K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, H. Zhao, J. F. Gilchrist, and N. Tansu, “Optimization of light extraction efficiency of III-Nitride light emitting diodes with self-assembled colloidal-based microlenses,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1218–1225 (2009).
[Crossref]

P. Kumnorkaew, Y. K. Ee, N. Tansu, and J. F. Gilchrist, “Investigation of the deposition of microsphere monolayers for fabrication of microlens arrays,” Langmuir 24(21), 12150–12157 (2008).
[Crossref] [PubMed]

Y.-K. Ee, R. A. Arif, N. Tansu, P. Kumnorkaew, and J. F. Gilchrist, “Enhancement of light extraction efficiency of InGaN quantum wells light emitting diodes using SiO2/polystyrene microlens arrays,” Appl. Phys. Lett. 91(22), 221107 (2007).
[Crossref]

Haskell, B. A.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[Crossref]

Hirayama, H.

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A 206(6), 1176–1182 (2009).
[Crossref]

H. Hirayama, T. Yatabe, N. Noguchi, T. Ohashi, and N. Kamata, “231–261 nm AlGaN deep-ultraviolet light-emitting diodes fabricated on AlN multilayer buffers grown by ammonia pulse-flow method on sapphire,” Appl. Phys. Lett. 91(7), 071901 (2007).
[Crossref]

Hu, E. L.

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

Huh, C.

C. Huh, K. S. Lee, E. J. Kang, and S. J. Park, “Improved light-output and electrical performance of InGaN-based light-emitting diode by microroughening of the p-GaN surface,” J. Appl. Phys. 93(11), 9383–9385 (2003).
[Crossref]

Iwasa, N.

S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, “High-brightness InGaN blue, green and yellow light-emitting diodes with quantum well structures,” Jpn. J. Appl. Phys. 34(Part 2, No. 7A), L797–L799 (1995).
[Crossref]

Kamata, N.

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A 206(6), 1176–1182 (2009).
[Crossref]

H. Hirayama, T. Yatabe, N. Noguchi, T. Ohashi, and N. Kamata, “231–261 nm AlGaN deep-ultraviolet light-emitting diodes fabricated on AlN multilayer buffers grown by ammonia pulse-flow method on sapphire,” Appl. Phys. Lett. 91(7), 071901 (2007).
[Crossref]

Kang, E. J.

C. Huh, K. S. Lee, E. J. Kang, and S. J. Park, “Improved light-output and electrical performance of InGaN-based light-emitting diode by microroughening of the p-GaN surface,” J. Appl. Phys. 93(11), 9383–9385 (2003).
[Crossref]

Kasu, M.

Y. Taniyasu and M. Kasu, “Polarization property of deep-ultraviolet light emission from C-plane AlN/GaN short-period superlattices,” Appl. Phys. Lett. 99(25), 251112 (2011).
[Crossref]

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]

Keller, S.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[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, J. K.

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S. Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Kim, M. H.

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

Koleske, D. D.

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

A. A. Allerman, M. H. Crawford, A. J. Fischer, K. H. A. Bogart, S. R. Lee, D. M. Follstaedt, P. P. Provencio, and D. D. Koleske, “Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys,” J. Cryst. Growth 272(1-4), 227–241 (2004).
[Crossref]

Koyama, T.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[Crossref]

Kumnorkaew, P.

X.-H. Li, R. Song, Y.-K. Ee, P. Kumnorkaew, J. F. Gilchrist, and N. Tansu, “Light extraction efficiency and radiation patterns of III-nitride light-emitting diodes with colloidal microlens arrays with various aspect ratios,” IEEE Photon. J. 3(3), 489–499 (2011).
[Crossref]

Y.-K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, H. Zhao, J. F. Gilchrist, and N. Tansu, “Optimization of light extraction efficiency of III-Nitride light emitting diodes with self-assembled colloidal-based microlenses,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1218–1225 (2009).
[Crossref]

P. Kumnorkaew, Y. K. Ee, N. Tansu, and J. F. Gilchrist, “Investigation of the deposition of microsphere monolayers for fabrication of microlens arrays,” Langmuir 24(21), 12150–12157 (2008).
[Crossref] [PubMed]

Y.-K. Ee, R. A. Arif, N. Tansu, P. Kumnorkaew, and J. F. Gilchrist, “Enhancement of light extraction efficiency of InGaN quantum wells light emitting diodes using SiO2/polystyrene microlens arrays,” Appl. Phys. Lett. 91(22), 221107 (2007).
[Crossref]

Kuokstis, E.

M. Asif Khan, M. Shatalov, H. P. Maruska, H. M. Wang, and E. Kuokstis, “III–nitride UV devices,” Jpn. J. Appl. Phys. 44(10), 7191–7206 (2005).
[Crossref]

Lai, P. T.

W. N. Ng, C. H. Leung, P. T. Lai, and H. W. Choi, “Nanostructuring GaN using microsphere lithography,” J. Vac. Sci. Technol. B 26(1), 76–79 (2008).
[Crossref]

Lee, K. S.

C. Huh, K. S. Lee, E. J. Kang, and S. J. Park, “Improved light-output and electrical performance of InGaN-based light-emitting diode by microroughening of the p-GaN surface,” J. Appl. Phys. 93(11), 9383–9385 (2003).
[Crossref]

Lee, S. R.

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

A. A. Allerman, M. H. Crawford, A. J. Fischer, K. H. A. Bogart, S. R. Lee, D. M. Follstaedt, P. P. Provencio, and D. D. Koleske, “Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys,” J. Cryst. Growth 272(1-4), 227–241 (2004).
[Crossref]

Lee, W.

J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
[Crossref]

Leung, C. H.

W. N. Ng, C. H. Leung, P. T. Lai, and H. W. Choi, “Nanostructuring GaN using microsphere lithography,” J. Vac. Sci. Technol. B 26(1), 76–79 (2008).
[Crossref]

Li, X.-H.

X.-H. Li, R. Song, Y.-K. Ee, P. Kumnorkaew, J. F. Gilchrist, and N. Tansu, “Light extraction efficiency and radiation patterns of III-nitride light-emitting diodes with colloidal microlens arrays with various aspect ratios,” IEEE Photon. J. 3(3), 489–499 (2011).
[Crossref]

Limb, J.

J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
[Crossref]

Lin, S. Y.

Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S. Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Liu, G.

Liu, J. P.

J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
[Crossref]

Liu, W.

Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S. Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Maruska, H. P.

M. Asif Khan, M. Shatalov, H. P. Maruska, H. M. Wang, and E. Kuokstis, “III–nitride UV devices,” Jpn. J. Appl. Phys. 44(10), 7191–7206 (2005).
[Crossref]

Masui, H.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[Crossref]

Megens, M. M.

J. J. Wierer, A. David, and M. M. Megens, “III-nitride photoniccrystal light-emitting diodes with high extraction efficiency,” Nat. Photonics 3(3), 163–169 (2009).
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Meyer, J. R.

I. Vurgaftman and J. R. Meyer, “Band parameters for nitrogen-containing semiconductors,” J. Appl. Phys. 94(6), 3675–3696 (2003).
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Mishra, U. K.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[Crossref]

Nagahama, S.

S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, “High-brightness InGaN blue, green and yellow light-emitting diodes with quantum well structures,” Jpn. J. Appl. Phys. 34(Part 2, No. 7A), L797–L799 (1995).
[Crossref]

Nakamura, S.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[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]

S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, “High-brightness InGaN blue, green and yellow light-emitting diodes with quantum well structures,” Jpn. J. Appl. Phys. 34(Part 2, No. 7A), L797–L799 (1995).
[Crossref]

Ng, W. N.

W. N. Ng, C. H. Leung, P. T. Lai, and H. W. Choi, “Nanostructuring GaN using microsphere lithography,” J. Vac. Sci. Technol. B 26(1), 76–79 (2008).
[Crossref]

Noguchi, N.

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A 206(6), 1176–1182 (2009).
[Crossref]

H. Hirayama, T. Yatabe, N. Noguchi, T. Ohashi, and N. Kamata, “231–261 nm AlGaN deep-ultraviolet light-emitting diodes fabricated on AlN multilayer buffers grown by ammonia pulse-flow method on sapphire,” Appl. Phys. Lett. 91(7), 071901 (2007).
[Crossref]

Norimatsu, J.

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A 206(6), 1176–1182 (2009).
[Crossref]

Ohashi, T.

H. Hirayama, T. Yatabe, N. Noguchi, T. Ohashi, and N. Kamata, “231–261 nm AlGaN deep-ultraviolet light-emitting diodes fabricated on AlN multilayer buffers grown by ammonia pulse-flow method on sapphire,” Appl. Phys. Lett. 91(7), 071901 (2007).
[Crossref]

Onuma, T.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[Crossref]

Park, S. J.

C. Huh, K. S. Lee, E. J. Kang, and S. J. Park, “Improved light-output and electrical performance of InGaN-based light-emitting diode by microroughening of the p-GaN surface,” J. Appl. Phys. 93(11), 9383–9385 (2003).
[Crossref]

Ponce, F. A.

J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
[Crossref]

Poplawsky, J. D.

Provencio, P. P.

A. A. Allerman, M. H. Crawford, A. J. Fischer, K. H. A. Bogart, S. R. Lee, D. M. Follstaedt, P. P. Provencio, and D. D. Koleske, “Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys,” J. Cryst. Growth 272(1-4), 227–241 (2004).
[Crossref]

Ryou, J.-H.

J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
[Crossref]

Schubert, E. F.

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S. Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Schubert, M. F.

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S. Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Senoh, M.

S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, “High-brightness InGaN blue, green and yellow light-emitting diodes with quantum well structures,” Jpn. J. Appl. Phys. 34(Part 2, No. 7A), L797–L799 (1995).
[Crossref]

Sharma, R.

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

Shatalov, M.

M. Asif Khan, M. Shatalov, H. P. Maruska, H. M. Wang, and E. Kuokstis, “III–nitride UV devices,” Jpn. J. Appl. Phys. 44(10), 7191–7206 (2005).
[Crossref]

Smart, J. A.

Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S. Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Song, R.

X.-H. Li, R. Song, Y.-K. Ee, P. Kumnorkaew, J. F. Gilchrist, and N. Tansu, “Light extraction efficiency and radiation patterns of III-nitride light-emitting diodes with colloidal microlens arrays with various aspect ratios,” IEEE Photon. J. 3(3), 489–499 (2011).
[Crossref]

Sota, T.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[Crossref]

Speck, J. S.

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[Crossref]

Takano, T.

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A 206(6), 1176–1182 (2009).
[Crossref]

Taniyasu, Y.

Y. Taniyasu and M. Kasu, “Polarization property of deep-ultraviolet light emission from C-plane AlN/GaN short-period superlattices,” Appl. Phys. Lett. 99(25), 251112 (2011).
[Crossref]

Tansu, N.

J. Zhang, H. Zhao, and N. Tansu, “Large optical gain AlGaN-Delta-GaN quantum wells laser active regions in mid- and deep-ultraviolet spectral regimes,” Appl. Phys. Lett. 98(17), 171111 (2011).
[Crossref]

H. Zhao, G. Liu, J. Zhang, J. D. Poplawsky, V. Dierolf, and N. Tansu, “Approaches for high internal quantum efficiency green InGaN light-emitting diodes with large overlap quantum wells,” Opt. Express 19(S4Suppl 4), A991–A1007 (2011).
[Crossref] [PubMed]

X.-H. Li, R. Song, Y.-K. Ee, P. Kumnorkaew, J. F. Gilchrist, and N. Tansu, “Light extraction efficiency and radiation patterns of III-nitride light-emitting diodes with colloidal microlens arrays with various aspect ratios,” IEEE Photon. J. 3(3), 489–499 (2011).
[Crossref]

J. Zhang, H. Zhao, and N. Tansu, “Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers,” Appl. Phys. Lett. 97(11), 111105 (2010).
[Crossref]

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Self-consistent analysis of strain-compensated InGaN-AlGaN quantum wells for lasers and light emitting diodes,” IEEE J. Quantum Electron. 45(1), 66–78 (2009).
[Crossref]

Y.-K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, H. Zhao, J. F. Gilchrist, and N. Tansu, “Optimization of light extraction efficiency of III-Nitride light emitting diodes with self-assembled colloidal-based microlenses,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1218–1225 (2009).
[Crossref]

H. Zhao, R. A. Arif, and N. Tansu, “Design analysis of staggered InGaN quantum wells light-emitting diodes at 500–540 nm,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1104–1114 (2009).
[Crossref]

P. Kumnorkaew, Y. K. Ee, N. Tansu, and J. F. Gilchrist, “Investigation of the deposition of microsphere monolayers for fabrication of microlens arrays,” Langmuir 24(21), 12150–12157 (2008).
[Crossref] [PubMed]

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Optical gain analysis of strain-compensated InGaN–AlGaN quantum well active regions for lasers emitting at 420-500 nm,” Opt. Quantum Electron. 40(5-6), 301–306 (2008).
[Crossref]

Y.-K. Ee, R. A. Arif, N. Tansu, P. Kumnorkaew, and J. F. Gilchrist, “Enhancement of light extraction efficiency of InGaN quantum wells light emitting diodes using SiO2/polystyrene microlens arrays,” Appl. Phys. Lett. 91(22), 221107 (2007).
[Crossref]

Thaler, G.

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

Tong, H.

Y.-K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, H. Zhao, J. F. Gilchrist, and N. Tansu, “Optimization of light extraction efficiency of III-Nitride light emitting diodes with self-assembled colloidal-based microlenses,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1218–1225 (2009).
[Crossref]

Tsubaki, K.

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A 206(6), 1176–1182 (2009).
[Crossref]

Vurgaftman, I.

I. Vurgaftman and J. R. Meyer, “Band parameters for nitrogen-containing semiconductors,” J. Appl. Phys. 94(6), 3675–3696 (2003).
[Crossref]

Wang, H. M.

M. Asif Khan, M. Shatalov, H. P. Maruska, H. M. Wang, and E. Kuokstis, “III–nitride UV devices,” Jpn. J. Appl. Phys. 44(10), 7191–7206 (2005).
[Crossref]

Wierer, J. J.

J. J. Wierer, A. David, and M. M. Megens, “III-nitride photoniccrystal light-emitting diodes with high extraction efficiency,” Nat. Photonics 3(3), 163–169 (2009).
[Crossref]

Wong, K.-K.

W. Y. Fu, K.-K. Wong, and H. W. Choi, “Close-packed hemiellipsoid arrays: a photonic band gap structure patterned by nanosphere lithography,” Appl. Phys. Lett. 95(13), 133125 (2009).
[Crossref]

Wu, Z. H.

J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
[Crossref]

Xi, Q.

Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S. Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

Yatabe, T.

H. Hirayama, T. Yatabe, N. Noguchi, T. Ohashi, and N. Kamata, “231–261 nm AlGaN deep-ultraviolet light-emitting diodes fabricated on AlN multilayer buffers grown by ammonia pulse-flow method on sapphire,” Appl. Phys. Lett. 91(7), 071901 (2007).
[Crossref]

Yoo, D.

J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
[Crossref]

Zhang, J.

J. Zhang, H. Zhao, and N. Tansu, “Large optical gain AlGaN-Delta-GaN quantum wells laser active regions in mid- and deep-ultraviolet spectral regimes,” Appl. Phys. Lett. 98(17), 171111 (2011).
[Crossref]

H. Zhao, G. Liu, J. Zhang, J. D. Poplawsky, V. Dierolf, and N. Tansu, “Approaches for high internal quantum efficiency green InGaN light-emitting diodes with large overlap quantum wells,” Opt. Express 19(S4Suppl 4), A991–A1007 (2011).
[Crossref] [PubMed]

J. Zhang, H. Zhao, and N. Tansu, “Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers,” Appl. Phys. Lett. 97(11), 111105 (2010).
[Crossref]

Zhao, H.

P. Zhao and H. Zhao, “Analysis of light extraction efficiency enhancement for thin-film-flip-chip InGaN quantum wells light-emitting diodes with GaN micro-domes,” Opt. Express 20(S5), A765–A776 (2012).
[Crossref]

J. Zhang, H. Zhao, and N. Tansu, “Large optical gain AlGaN-Delta-GaN quantum wells laser active regions in mid- and deep-ultraviolet spectral regimes,” Appl. Phys. Lett. 98(17), 171111 (2011).
[Crossref]

H. Zhao, G. Liu, J. Zhang, J. D. Poplawsky, V. Dierolf, and N. Tansu, “Approaches for high internal quantum efficiency green InGaN light-emitting diodes with large overlap quantum wells,” Opt. Express 19(S4Suppl 4), A991–A1007 (2011).
[Crossref] [PubMed]

J. Zhang, H. Zhao, and N. Tansu, “Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers,” Appl. Phys. Lett. 97(11), 111105 (2010).
[Crossref]

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Self-consistent analysis of strain-compensated InGaN-AlGaN quantum wells for lasers and light emitting diodes,” IEEE J. Quantum Electron. 45(1), 66–78 (2009).
[Crossref]

Y.-K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, H. Zhao, J. F. Gilchrist, and N. Tansu, “Optimization of light extraction efficiency of III-Nitride light emitting diodes with self-assembled colloidal-based microlenses,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1218–1225 (2009).
[Crossref]

H. Zhao, R. A. Arif, and N. Tansu, “Design analysis of staggered InGaN quantum wells light-emitting diodes at 500–540 nm,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1104–1114 (2009).
[Crossref]

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Optical gain analysis of strain-compensated InGaN–AlGaN quantum well active regions for lasers emitting at 420-500 nm,” Opt. Quantum Electron. 40(5-6), 301–306 (2008).
[Crossref]

Zhao, P.

Appl. Phys. Lett. (10)

H. Hirayama, T. Yatabe, N. Noguchi, T. Ohashi, and N. Kamata, “231–261 nm AlGaN deep-ultraviolet light-emitting diodes fabricated on AlN multilayer buffers grown by ammonia pulse-flow method on sapphire,” Appl. Phys. Lett. 91(7), 071901 (2007).
[Crossref]

Q. Dai, M. F. Schubert, M. H. Kim, J. K. Kim, E. F. Schubert, D. D. Koleske, M. H. Crawford, S. R. Lee, A. J. Fischer, G. Thaler, and M. A. Banas, “Internal quantum efficiency and nonradiative recombination coefficient of GaInN/GaN multiple quantum wells with different dislocation densities,” Appl. Phys. Lett. 94(11), 111109 (2009).
[Crossref]

J.-H. Ryou, W. Lee, J. Limb, D. Yoo, J. P. Liu, R. D. Dupuis, Z. H. Wu, A. M. Fischer, and F. A. Ponce, “Control of quantum-confined Stark effect in InGaN/GaN multiple quantum well active region by p-type layer for III-nitride-based visible light emitting diodes,” Appl. Phys. Lett. 92(10), 101113 (2008).
[Crossref]

T. Koyama, T. Onuma, H. Masui, A. Chakraborty, B. A. Haskell, S. Keller, U. K. Mishra, J. S. Speck, S. Nakamura, S. P. DenBaars, T. Sota, and S. F. Chichibu, “Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates,” Appl. Phys. Lett. 89(9), 091906 (2006).
[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]

Y.-K. Ee, R. A. Arif, N. Tansu, P. Kumnorkaew, and J. F. Gilchrist, “Enhancement of light extraction efficiency of InGaN quantum wells light emitting diodes using SiO2/polystyrene microlens arrays,” Appl. Phys. Lett. 91(22), 221107 (2007).
[Crossref]

W. Y. Fu, K.-K. Wong, and H. W. Choi, “Close-packed hemiellipsoid arrays: a photonic band gap structure patterned by nanosphere lithography,” Appl. Phys. Lett. 95(13), 133125 (2009).
[Crossref]

J. Zhang, H. Zhao, and N. Tansu, “Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers,” Appl. Phys. Lett. 97(11), 111105 (2010).
[Crossref]

J. Zhang, H. Zhao, and N. Tansu, “Large optical gain AlGaN-Delta-GaN quantum wells laser active regions in mid- and deep-ultraviolet spectral regimes,” Appl. Phys. Lett. 98(17), 171111 (2011).
[Crossref]

Y. Taniyasu and M. Kasu, “Polarization property of deep-ultraviolet light emission from C-plane AlN/GaN short-period superlattices,” Appl. Phys. Lett. 99(25), 251112 (2011).
[Crossref]

IEEE J. Quantum Electron. (2)

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Self-consistent analysis of strain-compensated InGaN-AlGaN quantum wells for lasers and light emitting diodes,” IEEE J. Quantum Electron. 45(1), 66–78 (2009).
[Crossref]

S. L. Chuang, “Optical gain of strained wurtzite GaN quantum-well lasers,” IEEE J. Quantum Electron. 32(10), 1791–1800 (1996).
[Crossref]

IEEE J. Sel. Top. Quantum Electron. (2)

Y.-K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, H. Zhao, J. F. Gilchrist, and N. Tansu, “Optimization of light extraction efficiency of III-Nitride light emitting diodes with self-assembled colloidal-based microlenses,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1218–1225 (2009).
[Crossref]

H. Zhao, R. A. Arif, and N. Tansu, “Design analysis of staggered InGaN quantum wells light-emitting diodes at 500–540 nm,” IEEE J. Sel. Top. Quantum Electron. 15(4), 1104–1114 (2009).
[Crossref]

IEEE Photon. J. (1)

X.-H. Li, R. Song, Y.-K. Ee, P. Kumnorkaew, J. F. Gilchrist, and N. Tansu, “Light extraction efficiency and radiation patterns of III-nitride light-emitting diodes with colloidal microlens arrays with various aspect ratios,” IEEE Photon. J. 3(3), 489–499 (2011).
[Crossref]

J. Appl. Phys. (2)

C. Huh, K. S. Lee, E. J. Kang, and S. J. Park, “Improved light-output and electrical performance of InGaN-based light-emitting diode by microroughening of the p-GaN surface,” J. Appl. Phys. 93(11), 9383–9385 (2003).
[Crossref]

I. Vurgaftman and J. R. Meyer, “Band parameters for nitrogen-containing semiconductors,” J. Appl. Phys. 94(6), 3675–3696 (2003).
[Crossref]

J. Cryst. Growth (1)

A. A. Allerman, M. H. Crawford, A. J. Fischer, K. H. A. Bogart, S. R. Lee, D. M. Follstaedt, P. P. Provencio, and D. D. Koleske, “Growth and design of deep-UV (240-290 nm) light emitting diodes using AlGaN alloys,” J. Cryst. Growth 272(1-4), 227–241 (2004).
[Crossref]

J. Vac. Sci. Technol. B (1)

W. N. Ng, C. H. Leung, P. T. Lai, and H. W. Choi, “Nanostructuring GaN using microsphere lithography,” J. Vac. Sci. Technol. B 26(1), 76–79 (2008).
[Crossref]

Jpn. J. Appl. Phys. (2)

S. Nakamura, M. Senoh, N. Iwasa, and S. Nagahama, “High-brightness InGaN blue, green and yellow light-emitting diodes with quantum well structures,” Jpn. J. Appl. Phys. 34(Part 2, No. 7A), L797–L799 (1995).
[Crossref]

M. Asif Khan, M. Shatalov, H. P. Maruska, H. M. Wang, and E. Kuokstis, “III–nitride UV devices,” Jpn. J. Appl. Phys. 44(10), 7191–7206 (2005).
[Crossref]

Langmuir (1)

P. Kumnorkaew, Y. K. Ee, N. Tansu, and J. F. Gilchrist, “Investigation of the deposition of microsphere monolayers for fabrication of microlens arrays,” Langmuir 24(21), 12150–12157 (2008).
[Crossref] [PubMed]

Nat. Photonics (3)

Q. Xi, M. F. Schubert, J. K. Kim, E. F. Schubert, M. Chen, S. Y. Lin, W. Liu, and J. A. Smart, “Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection,” Nat. Photonics 1, 176–179 (2007).

J. J. Wierer, A. David, and M. M. Megens, “III-nitride photoniccrystal light-emitting diodes with high extraction efficiency,” Nat. Photonics 3(3), 163–169 (2009).
[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]

Opt. Express (2)

Opt. Quantum Electron. (1)

H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Optical gain analysis of strain-compensated InGaN–AlGaN quantum well active regions for lasers emitting at 420-500 nm,” Opt. Quantum Electron. 40(5-6), 301–306 (2008).
[Crossref]

Phys. Status Solidi A (2)

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A 206(6), 1176–1182 (2009).
[Crossref]

M. Asif Khan, “AlGaN multiple quantum well based deep UV LEDs and their applications,” Phys. Status Solidi A 203(7), 1764–1770 (2006).
[Crossref]

Other (3)

Lumerical FDTD Solution.

M. Bass, ed., Handbook of Optics, Vol. 2: Devices, Measurements, and Properties (Optical Society of America, 1994).

I. Vurgaftman and J. R. Meyer, in Nitride Semiconductor Devices, J. Piprek, ed. (Wiley, 2007), Chap. 2.

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Figures (7)

Fig. 1
Fig. 1 2D Schematics of deep-UV AlGaN QWs LEDs with (a) flat surface; and (b) p-type micro-domes on top of the LEDs for enhancing light extraction efficiency.

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Fig. 2
Fig. 2 Spontaneous emission spectra (TE and TM modes) for AlxGa1-xN QWs LEDs with x = 0.58, 0.62, 0.66, and 0.7. TM spontaneous emission component becomes dominant when x>0.66.

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Fig. 3
Fig. 3 (a) Schematic of AlGaN QWs LEDs with p-type micro-hemispheres, where D represents the diameter of the micro-hemisphere and Ptype represents the thickness of the p-type layer; and (b) TM mode light extraction efficiency as a function of the TM dipole source position relative to the micro-hemispheres with D = 0 (flat surface), D = 100nm, D = 200nm, D = 300nm, D = 400nm, and D = 500nm.

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Fig. 4
Fig. 4 TM mode light extraction efficiency as a function of the TM dipole source position relative to the micro-domes with p-type layer thickness of Ptype = 300nm, Ptype = 350nm, Ptype = 400nm, and Ptype = 700nm. The micro-hemisphere diameter is set as D = 500nm.

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Fig. 5
Fig. 5 (a) Light extraction efficiency enhancement of the TM polarized spontaneous emission component for AlGaN QWs LEDs with AlGaN micro-hemispheres emitting at 250nm as a function of the micro-hemisphere diameter, and (b) Light extraction efficiency of the TM polarized spontaneous emission component for AlGaN QWs LEDs with AlGaN micro-hemispheres emitting at 250nm as a function of the p-AlGaN layer thickness. The micro-hemisphere diameter is 500nm. The light extraction efficiency of conventional deep UV LEDs with flat surface is plotted as a comparison.

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Fig. 6
Fig. 6 (a) Schematic of AlGaN QWs LEDs with p-type micro-domes, where D represents the diameter of the micro-dome and h represents the height of the micro-dome, and (b) Light extraction efficiency enhancement ratio of the TM polarized spontaneous emission component for AlGaN QWs LEDs with micro-domes emitting at 250nm as a function of the micro-dome height h. The yellow squares indicate the cases for micro-hemispheres (h = D/2).

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Fig. 7
Fig. 7 Far field emission pattern of the TM polarized spontaneous emission component for deep-UV AlGaN QWs LEDs with (a) flat surface (x3); (b) AlGaN micro-hemispheres (D = 200nm), (c) AlGaN micro-hemispheres (D = 500nm), and (d) AlGaN micro-domes (D = 200nm, h = 175nm). The p-type layer thickness is 300nm.

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