Abstract

A full structure 290-nm ultraviolet light-emitting diode (UV-LED) with a nanoporous n-AlGaN underlayer was fabricated by top via hole formation followed by high-voltage electrochemical etching. The 20 to 120 nm nanopores were prepared in regular doped n-AlGaN by adjusting the etching voltage. The comparison between the Raman spectrum and the photoluminescence wavelength shows that the biaxial stress in the nanoporous material is obviously relaxed. The photoluminescence enhancement was found to be highly dependent on the size of the pores. It not only improves the extraction efficiency of top-emitting transverse-electric (TE)-mode photons but also greatly improves the efficiency of side-emitting transverse-magnetic (TM)-mode photons. This leads to the polarization change of the side-emitting light from 0.08 to 0.242. The intensity of the electroluminescence was increased by 36.5% at 100 mA, and the efficiency droop at high current was found to decrease from 61% to 31%.

© 2020 Chinese Laser Press

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  39. C. De Santi, M. Meneghini, D. Monti, J. Glaab, M. Guttmann, J. Rass, S. Einfeldt, F. Mehnke, J. Enslin, T. Wernicke, M. Kneissl, G. Meneghesso, and E. Zanoni, “Recombination mechanisms and thermal droop in AlGaN-based UV-B LEDs,” Photon. Res. 5, A44–A51 (2017).
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    [Crossref]

2019 (3)

2018 (5)

C. Liu, Y. K. Ooi, S. M. Islam, H. Xing, D. Jena, and J. Zhang, “234  nm and 246  nm AlN-Delta-GaN quantum well deep ultraviolet light-emitting diodes,” Appl. Phys. Lett. 112, 011101 (2018).
[Crossref]

Y. Nagasawa and A. Hirano, “A review of AlGaN-based deep-ultraviolet light-emitting diodes on sapphire,” Appl. Sci. 8, 1264 (2018).
[Crossref]

S. Tan, J. Zhang, T. Egawa, and G. Chen, “Influence of quantum-well number and an AlN electron blocking layer on the electroluminescence properties of AlGaN deep ultraviolet light-emitting diodes,” Appl. Sci. 8, 2402 (2018).
[Crossref]

N. Susilo, S. Hagedorn, D. Jaeger, H. Miyake, U. Zeimer, C. Reich, B. Neuschulz, L. Sulmoni, M. Guttmann, F. Mehnke, C. Kuhn, T. Wernicke, M. Weyers, and M. Kneissl, “AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire,” Appl. Phys. Lett. 112, 041110 (2018).
[Crossref]

S. Wang, J. Dai, J. Hu, S. Zhang, L. Xu, H. Long, J. Chen, Q. Wan, H.-C. Kuo, and C. Chen, “Ultrahigh degree of optical polarization above 80% in AlGaN-based deep-ultraviolet LED with moth-eye microstructure,” ACS Photon. 5, 3534–3540 (2018).
[Crossref]

2017 (7)

Y. Guo, Y. Zhang, J. Yan, H. Xie, L. Liu, X. Chen, M. Hou, Z. Qin, J. Wang, and J. Li, “Light extraction enhancement of AlGaN-based ultraviolet light-emitting diodes by substrate sidewall roughening,” Appl. Phys. Lett. 111, 011102 (2017).
[Crossref]

Y. Zhang, R. Meng, Z.-H. Zhang, Q. Shi, L. Li, G. Liu, and W. Bi, “Effects of inclined sidewall structure with bottom metal air cavity on the light extraction efficiency for AlGaN-based deep ultraviolet light-emitting diodes,” IEEE Photon. J. 9, 1600709 (2017).
[Crossref]

S. Inoue, Naoki, and M. Taniguchi, “150  mW deep-ultraviolet light-emitting diodes with large-area AlN nanophotonic light-extraction structure emitting at 265  nm,” Appl. Phys. Lett. 110, 141106 (2017).
[Crossref]

T. Takano, T. Mino, J. Sakai, N. Noguchi, K. Tsubaki, and H. Hirayama, “Deep-ultraviolet light-emitting diodes with external quantum efficiency higher than 20% at 275  nm achieved by improving light-extraction efficiency,” Appl. Phys. Express 10, 031002 (2017).
[Crossref]

T. Y. Wang, C. T. Tasi, C. F. Lin, and D. S. Wuu, “85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering,” Sci. Rep. 7, 14422 (2017).
[Crossref]

T. Detchprohm, Y.-S. Liu, K. Mehta, S. Wang, H. Xie, T.-T. Kao, S.-C. Shen, P. D. Yoder, F. A. Ponce, and R. D. Dupuis, “Sub 250  nm deep-UV AlGaN/AlN distributed Bragg reflectors,” Appl. Phys. Lett. 110, 011105 (2017).
[Crossref]

C. De Santi, M. Meneghini, D. Monti, J. Glaab, M. Guttmann, J. Rass, S. Einfeldt, F. Mehnke, J. Enslin, T. Wernicke, M. Kneissl, G. Meneghesso, and E. Zanoni, “Recombination mechanisms and thermal droop in AlGaN-based UV-B LEDs,” Photon. Res. 5, A44–A51 (2017).
[Crossref]

2016 (4)

G. Yuan, K. Xiong, C. Zhang, Y. Li, and J. Han, “Optical engineering of modal gain in a III-nitride laser with nanoporous GaN,” ACS Photon. 3, 1604–1610 (2016).
[Crossref]

X. Chen, C. Ji, Y. Xiang, X. Kang, B. Shen, and T. Yu, “Angular distribution of polarized light and its effect on light extraction efficiency in AlGaN deep-ultraviolet light-emitting diodes,” Opt. Express 24, A935–A942 (2016).
[Crossref]

B. T. Tran, N. Maeda, M. Jo, D. Inoue, T. Kikitsu, and H. Hirayama, “Performance improvement of AlN crystal quality grown on patterned Si(111) substrate for deep UV-LED applications,” Sci. Rep. 6, 35681 (2016).
[Crossref]

J. W. Lee, J. H. Park, D. Y. Kim, E. F. Schubert, J. Kim, J. Lee, Y.-l. Kim, Y. Park, and J. K. Kim, “Arrays of truncated cone AlGaN deep-ultraviolet light-emitting diodes facilitating efficient outcoupling of in-plane emission,” ACS Photon. 3, 2030–2034 (2016).
[Crossref]

2015 (2)

Z. Bryan, I. Bryan, S. Mita, J. Tweedie, Z. Sitar, and R. Collazo, “Strain dependence on polarization properties of AlGaN and AlGaN-based ultraviolet lasers grown on AlN substrates,” Appl. Phys. Lett. 106, 232101 (2015).
[Crossref]

J. Yan, J. Wang, Y. Zhang, P. Cong, L. Sun, Y. Tian, C. Zhao, and J. Li, “AlGaN-based deep-ultraviolet light-emitting diodes grown on High-quality AlN template using MOVPE,” J. Cryst. Growth 414, 254–257 (2015).
[Crossref]

2014 (4)

J. J. Wierer, A. A. Allerman, I. Montano, and M. W. Moseley, “Influence of optical polarization on the improvement of light extraction efficiency from reflective scattering structures in AlGaN ultraviolet light-emitting diodes,” Appl. Phys. Lett. 105, 061106 (2014).
[Crossref]

Y. Takashima, R. Shimizu, M. Haraguchi, and Y. Naoi, “Polarized emission characteristics of UV-LED with subwavelength grating,” Jpn. J. Appl. Phys. 53, 072101 (2014).
[Crossref]

H. Hirayama, N. Maeda, S. Fujikawa, S. Toyoda, and N. Kamata, “Recent progress and future prospects of AlGaN-based high-efficiency deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys. 53, 100209 (2014).
[Crossref]

M. Hou, Z. Qin, C. He, J. Cai, X. Wang, and B. Shen, “Effect of injection current on the optical polarization of AlGaN-based ultraviolet light-emitting diodes,” Opt. Express 22, 19589–19594 (2014).
[Crossref]

2013 (2)

H.-Y. Ryu, I.-G. Choi, H.-S. Choi, and J.-I. Shim, “Investigation of light extraction efficiency in AlGaN deep-ultraviolet light-emitting diodes,” Appl. Phys. Express 6, 062101 (2013).
[Crossref]

J. R. Grandusky, J. Chen, S. R. Gibb, M. C. Mendrick, C. G. Moe, L. Rodak, G. A. Garrett, M. Wraback, and L. J. Schowalter, “270  nm pseudomorphic ultraviolet light-emitting diodes with over 60  mW continuous wave output power,” Appl. Phys. Express 6, 032101 (2013).
[Crossref]

2012 (4)

A. Najar, M. Gerland, and M. Jouiad, “Porosity-induced relaxation of strains in GaN layers studied by means of micro-indentation and optical spectroscopy,” J. Appl. Phys. 111, 093513 (2012).
[Crossref]

M. Shatalov, W. Sun, A. Lunev, X. Hu, A. Dobrinsky, Y. Bilenko, J. Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, and M. Wraback, “AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%,” Appl. Phys. Express 5, 082101 (2012).
[Crossref]

P.-M. Tu, J.-R. Chang, S.-C. Huang, S.-K. Yang, Y.-W. Lin, T.-C. Hung, C.-P. Hsu, and C.-Y. Chang, “Investigation of efficiency droop for UV LED with N-type AlGaN layer,” Proc. SPIE 8278, 82781B (2012).
[Crossref]

J. E. Northrup, C. L. Chua, Z. Yang, T. Wunderer, M. Kneissl, N. M. Johnson, and T. Kolbe, “Effect of strain and barrier composition on the polarization of light emission from AlGaN/AlN quantum wells,” Appl. Phys. Lett. 100, 021101 (2012).
[Crossref]

2011 (1)

J.-I. Chyi, M.-H. Lo, Y. Nanishi, Y.-J. Cheng, H.-C. Kuo, H. Morkoç, J. Piprek, S.-C. Wang, and E. Yoon, “Fabrication and lasing characteristics of GaN nanopillars,” Proc. SPIE 7939, 79391T (2011).
[Crossref]

2010 (2)

Y. Taniyasu and M. Kasu, “Surface 210  nm light emission from an AlN p-n junction light-emitting diode enhanced by A-plane growth orientation,” Appl. Phys. Lett. 96, 221110 (2010).
[Crossref]

T. Kolbe, A. Knauer, C. Chua, Z. Yang, S. Einfeldt, P. Vogt, N. M. Johnson, M. Weyers, and M. Kneissl, “Optical polarization characteristics of ultraviolet (In)(Al)GaN multiple quantum well light emitting diodes,” Appl. Phys. Lett. 97, 171105 (2010).
[Crossref]

2009 (1)

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, 1176–1182 (2009).
[Crossref]

2007 (2)

M. F. Schubert, S. Chhajed, J. K. Kim, E. F. Schubert, and J. Cho, “Polarization of light emission by 460  nm GaInN/GaN light-emitting diodes grown on (0001) oriented sapphire substrates,” Appl. Phys. Lett. 91, 051117 (2007).
[Crossref]

H. Hartono, C. B. Soh, S. Y. Chow, S. J. Chua, and E. A. Fitzgerald, “Reduction of threading dislocation density in GaN grown on strain relaxed nanoporous GaN template,” Appl. Phys. Lett. 90, 171917 (2007).
[Crossref]

2004 (1)

K. B. Nam, J. Li, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Unique optical properties of AlGaN alloys and related ultraviolet emitters,” Appl. Phys. Lett. 84, 5264–5266 (2004).
[Crossref]

2002 (1)

V. Y. Davydov, I. N. Goncharuk, A. N. Smirnov, A. E. Nikolaev, W. V. Lundin, A. S. Usikov, A. A. Klochikhin, J. Aderhold, J. Graul, O. Semchinova, and H. Harima, “Composition dependence of optical phonon energies and Raman line broadening in hexagonal AlxGa1–xN alloys,” Phys. Rev. B 65, 125203 (2002).
[Crossref]

Aderhold, J.

V. Y. Davydov, I. N. Goncharuk, A. N. Smirnov, A. E. Nikolaev, W. V. Lundin, A. S. Usikov, A. A. Klochikhin, J. Aderhold, J. Graul, O. Semchinova, and H. Harima, “Composition dependence of optical phonon energies and Raman line broadening in hexagonal AlxGa1–xN alloys,” Phys. Rev. B 65, 125203 (2002).
[Crossref]

Allerman, A. A.

J. J. Wierer, A. A. Allerman, I. Montano, and M. W. Moseley, “Influence of optical polarization on the improvement of light extraction efficiency from reflective scattering structures in AlGaN ultraviolet light-emitting diodes,” Appl. Phys. Lett. 105, 061106 (2014).
[Crossref]

Bi, W.

Y. Zhang, R. Meng, Z.-H. Zhang, Q. Shi, L. Li, G. Liu, and W. Bi, “Effects of inclined sidewall structure with bottom metal air cavity on the light extraction efficiency for AlGaN-based deep ultraviolet light-emitting diodes,” IEEE Photon. J. 9, 1600709 (2017).
[Crossref]

Bilenko, Y.

M. Shatalov, W. Sun, A. Lunev, X. Hu, A. Dobrinsky, Y. Bilenko, J. Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, and M. Wraback, “AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%,” Appl. Phys. Express 5, 082101 (2012).
[Crossref]

Bryan, I.

Z. Bryan, I. Bryan, S. Mita, J. Tweedie, Z. Sitar, and R. Collazo, “Strain dependence on polarization properties of AlGaN and AlGaN-based ultraviolet lasers grown on AlN substrates,” Appl. Phys. Lett. 106, 232101 (2015).
[Crossref]

Bryan, Z.

Z. Bryan, I. Bryan, S. Mita, J. Tweedie, Z. Sitar, and R. Collazo, “Strain dependence on polarization properties of AlGaN and AlGaN-based ultraviolet lasers grown on AlN substrates,” Appl. Phys. Lett. 106, 232101 (2015).
[Crossref]

Cai, J.

Chang, C.-Y.

P.-M. Tu, J.-R. Chang, S.-C. Huang, S.-K. Yang, Y.-W. Lin, T.-C. Hung, C.-P. Hsu, and C.-Y. Chang, “Investigation of efficiency droop for UV LED with N-type AlGaN layer,” Proc. SPIE 8278, 82781B (2012).
[Crossref]

Chang, J.-R.

P.-M. Tu, J.-R. Chang, S.-C. Huang, S.-K. Yang, Y.-W. Lin, T.-C. Hung, C.-P. Hsu, and C.-Y. Chang, “Investigation of efficiency droop for UV LED with N-type AlGaN layer,” Proc. SPIE 8278, 82781B (2012).
[Crossref]

Chen, C.

S. Wang, J. Dai, J. Hu, S. Zhang, L. Xu, H. Long, J. Chen, Q. Wan, H.-C. Kuo, and C. Chen, “Ultrahigh degree of optical polarization above 80% in AlGaN-based deep-ultraviolet LED with moth-eye microstructure,” ACS Photon. 5, 3534–3540 (2018).
[Crossref]

Chen, G.

S. Tan, J. Zhang, T. Egawa, and G. Chen, “Influence of quantum-well number and an AlN electron blocking layer on the electroluminescence properties of AlGaN deep ultraviolet light-emitting diodes,” Appl. Sci. 8, 2402 (2018).
[Crossref]

Chen, J.

S. Wang, J. Dai, J. Hu, S. Zhang, L. Xu, H. Long, J. Chen, Q. Wan, H.-C. Kuo, and C. Chen, “Ultrahigh degree of optical polarization above 80% in AlGaN-based deep-ultraviolet LED with moth-eye microstructure,” ACS Photon. 5, 3534–3540 (2018).
[Crossref]

J. R. Grandusky, J. Chen, S. R. Gibb, M. C. Mendrick, C. G. Moe, L. Rodak, G. A. Garrett, M. Wraback, and L. J. Schowalter, “270  nm pseudomorphic ultraviolet light-emitting diodes with over 60  mW continuous wave output power,” Appl. Phys. Express 6, 032101 (2013).
[Crossref]

Chen, X.

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M. F. Schubert, S. Chhajed, J. K. Kim, E. F. Schubert, and J. Cho, “Polarization of light emission by 460  nm GaInN/GaN light-emitting diodes grown on (0001) oriented sapphire substrates,” Appl. Phys. Lett. 91, 051117 (2007).
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J. E. Northrup, C. L. Chua, Z. Yang, T. Wunderer, M. Kneissl, N. M. Johnson, and T. Kolbe, “Effect of strain and barrier composition on the polarization of light emission from AlGaN/AlN quantum wells,” Appl. Phys. Lett. 100, 021101 (2012).
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H. Hartono, C. B. Soh, S. Y. Chow, S. J. Chua, and E. A. Fitzgerald, “Reduction of threading dislocation density in GaN grown on strain relaxed nanoporous GaN template,” Appl. Phys. Lett. 90, 171917 (2007).
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J.-I. Chyi, M.-H. Lo, Y. Nanishi, Y.-J. Cheng, H.-C. Kuo, H. Morkoç, J. Piprek, S.-C. Wang, and E. Yoon, “Fabrication and lasing characteristics of GaN nanopillars,” Proc. SPIE 7939, 79391T (2011).
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V. Y. Davydov, I. N. Goncharuk, A. N. Smirnov, A. E. Nikolaev, W. V. Lundin, A. S. Usikov, A. A. Klochikhin, J. Aderhold, J. Graul, O. Semchinova, and H. Harima, “Composition dependence of optical phonon energies and Raman line broadening in hexagonal AlxGa1–xN alloys,” Phys. Rev. B 65, 125203 (2002).
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M. Shatalov, W. Sun, A. Lunev, X. Hu, A. Dobrinsky, Y. Bilenko, J. Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, and M. Wraback, “AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%,” Appl. Phys. Express 5, 082101 (2012).
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T. Detchprohm, Y.-S. Liu, K. Mehta, S. Wang, H. Xie, T.-T. Kao, S.-C. Shen, P. D. Yoder, F. A. Ponce, and R. D. Dupuis, “Sub 250  nm deep-UV AlGaN/AlN distributed Bragg reflectors,” Appl. Phys. Lett. 110, 011105 (2017).
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C. De Santi, M. Meneghini, D. Monti, J. Glaab, M. Guttmann, J. Rass, S. Einfeldt, F. Mehnke, J. Enslin, T. Wernicke, M. Kneissl, G. Meneghesso, and E. Zanoni, “Recombination mechanisms and thermal droop in AlGaN-based UV-B LEDs,” Photon. Res. 5, A44–A51 (2017).
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T. Kolbe, A. Knauer, C. Chua, Z. Yang, S. Einfeldt, P. Vogt, N. M. Johnson, M. Weyers, and M. Kneissl, “Optical polarization characteristics of ultraviolet (In)(Al)GaN multiple quantum well light emitting diodes,” Appl. Phys. Lett. 97, 171105 (2010).
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Enslin, J.

Fitzgerald, E. A.

H. Hartono, C. B. Soh, S. Y. Chow, S. J. Chua, and E. A. Fitzgerald, “Reduction of threading dislocation density in GaN grown on strain relaxed nanoporous GaN template,” Appl. Phys. Lett. 90, 171917 (2007).
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H. Hirayama, N. Maeda, S. Fujikawa, S. Toyoda, and N. Kamata, “Recent progress and future prospects of AlGaN-based high-efficiency deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys. 53, 100209 (2014).
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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, 1176–1182 (2009).
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M. Shatalov, W. Sun, A. Lunev, X. Hu, A. Dobrinsky, Y. Bilenko, J. Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, and M. Wraback, “AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%,” Appl. Phys. Express 5, 082101 (2012).
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J. R. Grandusky, J. Chen, S. R. Gibb, M. C. Mendrick, C. G. Moe, L. Rodak, G. A. Garrett, M. Wraback, and L. J. Schowalter, “270  nm pseudomorphic ultraviolet light-emitting diodes with over 60  mW continuous wave output power,” Appl. Phys. Express 6, 032101 (2013).
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M. Shatalov, W. Sun, A. Lunev, X. Hu, A. Dobrinsky, Y. Bilenko, J. Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, and M. Wraback, “AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%,” Appl. Phys. Express 5, 082101 (2012).
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A. Najar, M. Gerland, and M. Jouiad, “Porosity-induced relaxation of strains in GaN layers studied by means of micro-indentation and optical spectroscopy,” J. Appl. Phys. 111, 093513 (2012).
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Goncharuk, I. N.

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J. R. Grandusky, J. Chen, S. R. Gibb, M. C. Mendrick, C. G. Moe, L. Rodak, G. A. Garrett, M. Wraback, and L. J. Schowalter, “270  nm pseudomorphic ultraviolet light-emitting diodes with over 60  mW continuous wave output power,” Appl. Phys. Express 6, 032101 (2013).
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V. Y. Davydov, I. N. Goncharuk, A. N. Smirnov, A. E. Nikolaev, W. V. Lundin, A. S. Usikov, A. A. Klochikhin, J. Aderhold, J. Graul, O. Semchinova, and H. Harima, “Composition dependence of optical phonon energies and Raman line broadening in hexagonal AlxGa1–xN alloys,” Phys. Rev. B 65, 125203 (2002).
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Y. Guo, Y. Zhang, J. Yan, H. Xie, L. Liu, X. Chen, M. Hou, Z. Qin, J. Wang, and J. Li, “Light extraction enhancement of AlGaN-based ultraviolet light-emitting diodes by substrate sidewall roughening,” Appl. Phys. Lett. 111, 011102 (2017).
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Guo, Y. N.

Guttmann, M.

N. Susilo, S. Hagedorn, D. Jaeger, H. Miyake, U. Zeimer, C. Reich, B. Neuschulz, L. Sulmoni, M. Guttmann, F. Mehnke, C. Kuhn, T. Wernicke, M. Weyers, and M. Kneissl, “AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire,” Appl. Phys. Lett. 112, 041110 (2018).
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C. De Santi, M. Meneghini, D. Monti, J. Glaab, M. Guttmann, J. Rass, S. Einfeldt, F. Mehnke, J. Enslin, T. Wernicke, M. Kneissl, G. Meneghesso, and E. Zanoni, “Recombination mechanisms and thermal droop in AlGaN-based UV-B LEDs,” Photon. Res. 5, A44–A51 (2017).
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N. Susilo, S. Hagedorn, D. Jaeger, H. Miyake, U. Zeimer, C. Reich, B. Neuschulz, L. Sulmoni, M. Guttmann, F. Mehnke, C. Kuhn, T. Wernicke, M. Weyers, and M. Kneissl, “AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire,” Appl. Phys. Lett. 112, 041110 (2018).
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V. Y. Davydov, I. N. Goncharuk, A. N. Smirnov, A. E. Nikolaev, W. V. Lundin, A. S. Usikov, A. A. Klochikhin, J. Aderhold, J. Graul, O. Semchinova, and H. Harima, “Composition dependence of optical phonon energies and Raman line broadening in hexagonal AlxGa1–xN alloys,” Phys. Rev. B 65, 125203 (2002).
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H. Hartono, C. B. Soh, S. Y. Chow, S. J. Chua, and E. A. Fitzgerald, “Reduction of threading dislocation density in GaN grown on strain relaxed nanoporous GaN template,” Appl. Phys. Lett. 90, 171917 (2007).
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T. Takano, T. Mino, J. Sakai, N. Noguchi, K. Tsubaki, and H. Hirayama, “Deep-ultraviolet light-emitting diodes with external quantum efficiency higher than 20% at 275  nm achieved by improving light-extraction efficiency,” Appl. Phys. Express 10, 031002 (2017).
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B. T. Tran, N. Maeda, M. Jo, D. Inoue, T. Kikitsu, and H. Hirayama, “Performance improvement of AlN crystal quality grown on patterned Si(111) substrate for deep UV-LED applications,” Sci. Rep. 6, 35681 (2016).
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H. Hirayama, N. Maeda, S. Fujikawa, S. Toyoda, and N. Kamata, “Recent progress and future prospects of AlGaN-based high-efficiency deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys. 53, 100209 (2014).
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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, 1176–1182 (2009).
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Y. Guo, Y. Zhang, J. Yan, H. Xie, L. Liu, X. Chen, M. Hou, Z. Qin, J. Wang, and J. Li, “Light extraction enhancement of AlGaN-based ultraviolet light-emitting diodes by substrate sidewall roughening,” Appl. Phys. Lett. 111, 011102 (2017).
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M. Hou, Z. Qin, C. He, J. Cai, X. Wang, and B. Shen, “Effect of injection current on the optical polarization of AlGaN-based ultraviolet light-emitting diodes,” Opt. Express 22, 19589–19594 (2014).
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P.-M. Tu, J.-R. Chang, S.-C. Huang, S.-K. Yang, Y.-W. Lin, T.-C. Hung, C.-P. Hsu, and C.-Y. Chang, “Investigation of efficiency droop for UV LED with N-type AlGaN layer,” Proc. SPIE 8278, 82781B (2012).
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H. Hu, S. Zhou, H. Wan, X. Liu, N. Li, and H. Xu, “Effect of strain relaxation on performance of InGaN/GaN green LEDs grown on 4-inch sapphire substrate with sputtered AlN nucleation layer,” Sci. Rep. 9, 3447 (2019).
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S. Wang, J. Dai, J. Hu, S. Zhang, L. Xu, H. Long, J. Chen, Q. Wan, H.-C. Kuo, and C. Chen, “Ultrahigh degree of optical polarization above 80% in AlGaN-based deep-ultraviolet LED with moth-eye microstructure,” ACS Photon. 5, 3534–3540 (2018).
[Crossref]

Hu, X.

M. Shatalov, W. Sun, A. Lunev, X. Hu, A. Dobrinsky, Y. Bilenko, J. Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, and M. Wraback, “AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%,” Appl. Phys. Express 5, 082101 (2012).
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P.-M. Tu, J.-R. Chang, S.-C. Huang, S.-K. Yang, Y.-W. Lin, T.-C. Hung, C.-P. Hsu, and C.-Y. Chang, “Investigation of efficiency droop for UV LED with N-type AlGaN layer,” Proc. SPIE 8278, 82781B (2012).
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P.-M. Tu, J.-R. Chang, S.-C. Huang, S.-K. Yang, Y.-W. Lin, T.-C. Hung, C.-P. Hsu, and C.-Y. Chang, “Investigation of efficiency droop for UV LED with N-type AlGaN layer,” Proc. SPIE 8278, 82781B (2012).
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B. T. Tran, N. Maeda, M. Jo, D. Inoue, T. Kikitsu, and H. Hirayama, “Performance improvement of AlN crystal quality grown on patterned Si(111) substrate for deep UV-LED applications,” Sci. Rep. 6, 35681 (2016).
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S. Inoue, Naoki, and M. Taniguchi, “150  mW deep-ultraviolet light-emitting diodes with large-area AlN nanophotonic light-extraction structure emitting at 265  nm,” Appl. Phys. Lett. 110, 141106 (2017).
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N. Susilo, S. Hagedorn, D. Jaeger, H. Miyake, U. Zeimer, C. Reich, B. Neuschulz, L. Sulmoni, M. Guttmann, F. Mehnke, C. Kuhn, T. Wernicke, M. Weyers, and M. Kneissl, “AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire,” Appl. Phys. Lett. 112, 041110 (2018).
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B. T. Tran, N. Maeda, M. Jo, D. Inoue, T. Kikitsu, and H. Hirayama, “Performance improvement of AlN crystal quality grown on patterned Si(111) substrate for deep UV-LED applications,” Sci. Rep. 6, 35681 (2016).
[Crossref]

Johnson, N. M.

J. E. Northrup, C. L. Chua, Z. Yang, T. Wunderer, M. Kneissl, N. M. Johnson, and T. Kolbe, “Effect of strain and barrier composition on the polarization of light emission from AlGaN/AlN quantum wells,” Appl. Phys. Lett. 100, 021101 (2012).
[Crossref]

T. Kolbe, A. Knauer, C. Chua, Z. Yang, S. Einfeldt, P. Vogt, N. M. Johnson, M. Weyers, and M. Kneissl, “Optical polarization characteristics of ultraviolet (In)(Al)GaN multiple quantum well light emitting diodes,” Appl. Phys. Lett. 97, 171105 (2010).
[Crossref]

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A. Najar, M. Gerland, and M. Jouiad, “Porosity-induced relaxation of strains in GaN layers studied by means of micro-indentation and optical spectroscopy,” J. Appl. Phys. 111, 093513 (2012).
[Crossref]

Kamata, N.

H. Hirayama, N. Maeda, S. Fujikawa, S. Toyoda, and N. Kamata, “Recent progress and future prospects of AlGaN-based high-efficiency deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys. 53, 100209 (2014).
[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, 1176–1182 (2009).
[Crossref]

Kang, X.

Kao, T.-T.

T. Detchprohm, Y.-S. Liu, K. Mehta, S. Wang, H. Xie, T.-T. Kao, S.-C. Shen, P. D. Yoder, F. A. Ponce, and R. D. Dupuis, “Sub 250  nm deep-UV AlGaN/AlN distributed Bragg reflectors,” Appl. Phys. Lett. 110, 011105 (2017).
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Y. Taniyasu and M. Kasu, “Surface 210  nm light emission from an AlN p-n junction light-emitting diode enhanced by A-plane growth orientation,” Appl. Phys. Lett. 96, 221110 (2010).
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B. T. Tran, N. Maeda, M. Jo, D. Inoue, T. Kikitsu, and H. Hirayama, “Performance improvement of AlN crystal quality grown on patterned Si(111) substrate for deep UV-LED applications,” Sci. Rep. 6, 35681 (2016).
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J. W. Lee, J. H. Park, D. Y. Kim, E. F. Schubert, J. Kim, J. Lee, Y.-l. Kim, Y. Park, and J. K. Kim, “Arrays of truncated cone AlGaN deep-ultraviolet light-emitting diodes facilitating efficient outcoupling of in-plane emission,” ACS Photon. 3, 2030–2034 (2016).
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J. W. Lee, J. H. Park, D. Y. Kim, E. F. Schubert, J. Kim, J. Lee, Y.-l. Kim, Y. Park, and J. K. Kim, “Arrays of truncated cone AlGaN deep-ultraviolet light-emitting diodes facilitating efficient outcoupling of in-plane emission,” ACS Photon. 3, 2030–2034 (2016).
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M. F. Schubert, S. Chhajed, J. K. Kim, E. F. Schubert, and J. Cho, “Polarization of light emission by 460  nm GaInN/GaN light-emitting diodes grown on (0001) oriented sapphire substrates,” Appl. Phys. Lett. 91, 051117 (2007).
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Kim, S.-J.

Kim, Y.-l.

J. W. Lee, J. H. Park, D. Y. Kim, E. F. Schubert, J. Kim, J. Lee, Y.-l. Kim, Y. Park, and J. K. Kim, “Arrays of truncated cone AlGaN deep-ultraviolet light-emitting diodes facilitating efficient outcoupling of in-plane emission,” ACS Photon. 3, 2030–2034 (2016).
[Crossref]

Klochikhin, A. A.

V. Y. Davydov, I. N. Goncharuk, A. N. Smirnov, A. E. Nikolaev, W. V. Lundin, A. S. Usikov, A. A. Klochikhin, J. Aderhold, J. Graul, O. Semchinova, and H. Harima, “Composition dependence of optical phonon energies and Raman line broadening in hexagonal AlxGa1–xN alloys,” Phys. Rev. B 65, 125203 (2002).
[Crossref]

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T. Kolbe, A. Knauer, C. Chua, Z. Yang, S. Einfeldt, P. Vogt, N. M. Johnson, M. Weyers, and M. Kneissl, “Optical polarization characteristics of ultraviolet (In)(Al)GaN multiple quantum well light emitting diodes,” Appl. Phys. Lett. 97, 171105 (2010).
[Crossref]

Kneissl, M.

N. Susilo, S. Hagedorn, D. Jaeger, H. Miyake, U. Zeimer, C. Reich, B. Neuschulz, L. Sulmoni, M. Guttmann, F. Mehnke, C. Kuhn, T. Wernicke, M. Weyers, and M. Kneissl, “AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire,” Appl. Phys. Lett. 112, 041110 (2018).
[Crossref]

C. De Santi, M. Meneghini, D. Monti, J. Glaab, M. Guttmann, J. Rass, S. Einfeldt, F. Mehnke, J. Enslin, T. Wernicke, M. Kneissl, G. Meneghesso, and E. Zanoni, “Recombination mechanisms and thermal droop in AlGaN-based UV-B LEDs,” Photon. Res. 5, A44–A51 (2017).
[Crossref]

J. E. Northrup, C. L. Chua, Z. Yang, T. Wunderer, M. Kneissl, N. M. Johnson, and T. Kolbe, “Effect of strain and barrier composition on the polarization of light emission from AlGaN/AlN quantum wells,” Appl. Phys. Lett. 100, 021101 (2012).
[Crossref]

T. Kolbe, A. Knauer, C. Chua, Z. Yang, S. Einfeldt, P. Vogt, N. M. Johnson, M. Weyers, and M. Kneissl, “Optical polarization characteristics of ultraviolet (In)(Al)GaN multiple quantum well light emitting diodes,” Appl. Phys. Lett. 97, 171105 (2010).
[Crossref]

Kolbe, T.

J. E. Northrup, C. L. Chua, Z. Yang, T. Wunderer, M. Kneissl, N. M. Johnson, and T. Kolbe, “Effect of strain and barrier composition on the polarization of light emission from AlGaN/AlN quantum wells,” Appl. Phys. Lett. 100, 021101 (2012).
[Crossref]

T. Kolbe, A. Knauer, C. Chua, Z. Yang, S. Einfeldt, P. Vogt, N. M. Johnson, M. Weyers, and M. Kneissl, “Optical polarization characteristics of ultraviolet (In)(Al)GaN multiple quantum well light emitting diodes,” Appl. Phys. Lett. 97, 171105 (2010).
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N. Susilo, S. Hagedorn, D. Jaeger, H. Miyake, U. Zeimer, C. Reich, B. Neuschulz, L. Sulmoni, M. Guttmann, F. Mehnke, C. Kuhn, T. Wernicke, M. Weyers, and M. Kneissl, “AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire,” Appl. Phys. Lett. 112, 041110 (2018).
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J. W. Lee, J. H. Park, D. Y. Kim, E. F. Schubert, J. Kim, J. Lee, Y.-l. Kim, Y. Park, and J. K. Kim, “Arrays of truncated cone AlGaN deep-ultraviolet light-emitting diodes facilitating efficient outcoupling of in-plane emission,” ACS Photon. 3, 2030–2034 (2016).
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Li, L.

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Park, Y.

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J. R. Grandusky, J. Chen, S. R. Gibb, M. C. Mendrick, C. G. Moe, L. Rodak, G. A. Garrett, M. Wraback, and L. J. Schowalter, “270  nm pseudomorphic ultraviolet light-emitting diodes with over 60  mW continuous wave output power,” Appl. Phys. Express 6, 032101 (2013).
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H.-Y. Ryu, I.-G. Choi, H.-S. Choi, and J.-I. Shim, “Investigation of light extraction efficiency in AlGaN deep-ultraviolet light-emitting diodes,” Appl. Phys. Express 6, 062101 (2013).
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T. Takano, T. Mino, J. Sakai, N. Noguchi, K. Tsubaki, and H. Hirayama, “Deep-ultraviolet light-emitting diodes with external quantum efficiency higher than 20% at 275  nm achieved by improving light-extraction efficiency,” Appl. Phys. Express 10, 031002 (2017).
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J. R. Grandusky, J. Chen, S. R. Gibb, M. C. Mendrick, C. G. Moe, L. Rodak, G. A. Garrett, M. Wraback, and L. J. Schowalter, “270  nm pseudomorphic ultraviolet light-emitting diodes with over 60  mW continuous wave output power,” Appl. Phys. Express 6, 032101 (2013).
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J. W. Lee, J. H. Park, D. Y. Kim, E. F. Schubert, J. Kim, J. Lee, Y.-l. Kim, Y. Park, and J. K. Kim, “Arrays of truncated cone AlGaN deep-ultraviolet light-emitting diodes facilitating efficient outcoupling of in-plane emission,” ACS Photon. 3, 2030–2034 (2016).
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M. Shatalov, W. Sun, A. Lunev, X. Hu, A. Dobrinsky, Y. Bilenko, J. Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, and M. Wraback, “AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%,” Appl. Phys. Express 5, 082101 (2012).
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Z. Bryan, I. Bryan, S. Mita, J. Tweedie, Z. Sitar, and R. Collazo, “Strain dependence on polarization properties of AlGaN and AlGaN-based ultraviolet lasers grown on AlN substrates,” Appl. Phys. Lett. 106, 232101 (2015).
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J. Yan, J. Wang, Y. Zhang, P. Cong, L. Sun, Y. Tian, C. Zhao, and J. Li, “AlGaN-based deep-ultraviolet light-emitting diodes grown on High-quality AlN template using MOVPE,” J. Cryst. Growth 414, 254–257 (2015).
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M. Shatalov, W. Sun, A. Lunev, X. Hu, A. Dobrinsky, Y. Bilenko, J. Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, and M. Wraback, “AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%,” Appl. Phys. Express 5, 082101 (2012).
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T. Takano, T. Mino, J. Sakai, N. Noguchi, K. Tsubaki, and H. Hirayama, “Deep-ultraviolet light-emitting diodes with external quantum efficiency higher than 20% at 275  nm achieved by improving light-extraction efficiency,” Appl. Phys. Express 10, 031002 (2017).
[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, 1176–1182 (2009).
[Crossref]

Takashima, Y.

Y. Takashima, R. Shimizu, M. Haraguchi, and Y. Naoi, “Polarized emission characteristics of UV-LED with subwavelength grating,” Jpn. J. Appl. Phys. 53, 072101 (2014).
[Crossref]

Tan, S.

S. Tan, J. Zhang, T. Egawa, and G. Chen, “Influence of quantum-well number and an AlN electron blocking layer on the electroluminescence properties of AlGaN deep ultraviolet light-emitting diodes,” Appl. Sci. 8, 2402 (2018).
[Crossref]

Taniguchi, M.

S. Inoue, Naoki, and M. Taniguchi, “150  mW deep-ultraviolet light-emitting diodes with large-area AlN nanophotonic light-extraction structure emitting at 265  nm,” Appl. Phys. Lett. 110, 141106 (2017).
[Crossref]

Taniyasu, Y.

Y. Taniyasu and M. Kasu, “Surface 210  nm light emission from an AlN p-n junction light-emitting diode enhanced by A-plane growth orientation,” Appl. Phys. Lett. 96, 221110 (2010).
[Crossref]

Tasi, C. T.

T. Y. Wang, C. T. Tasi, C. F. Lin, and D. S. Wuu, “85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering,” Sci. Rep. 7, 14422 (2017).
[Crossref]

Tian, Y.

J. Yan, J. Wang, Y. Zhang, P. Cong, L. Sun, Y. Tian, C. Zhao, and J. Li, “AlGaN-based deep-ultraviolet light-emitting diodes grown on High-quality AlN template using MOVPE,” J. Cryst. Growth 414, 254–257 (2015).
[Crossref]

Toyoda, S.

H. Hirayama, N. Maeda, S. Fujikawa, S. Toyoda, and N. Kamata, “Recent progress and future prospects of AlGaN-based high-efficiency deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys. 53, 100209 (2014).
[Crossref]

Tran, B. T.

B. T. Tran, N. Maeda, M. Jo, D. Inoue, T. Kikitsu, and H. Hirayama, “Performance improvement of AlN crystal quality grown on patterned Si(111) substrate for deep UV-LED applications,” Sci. Rep. 6, 35681 (2016).
[Crossref]

Tsubaki, K.

T. Takano, T. Mino, J. Sakai, N. Noguchi, K. Tsubaki, and H. Hirayama, “Deep-ultraviolet light-emitting diodes with external quantum efficiency higher than 20% at 275  nm achieved by improving light-extraction efficiency,” Appl. Phys. Express 10, 031002 (2017).
[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, 1176–1182 (2009).
[Crossref]

Tu, P.-M.

P.-M. Tu, J.-R. Chang, S.-C. Huang, S.-K. Yang, Y.-W. Lin, T.-C. Hung, C.-P. Hsu, and C.-Y. Chang, “Investigation of efficiency droop for UV LED with N-type AlGaN layer,” Proc. SPIE 8278, 82781B (2012).
[Crossref]

Tweedie, J.

Z. Bryan, I. Bryan, S. Mita, J. Tweedie, Z. Sitar, and R. Collazo, “Strain dependence on polarization properties of AlGaN and AlGaN-based ultraviolet lasers grown on AlN substrates,” Appl. Phys. Lett. 106, 232101 (2015).
[Crossref]

Usikov, A. S.

V. Y. Davydov, I. N. Goncharuk, A. N. Smirnov, A. E. Nikolaev, W. V. Lundin, A. S. Usikov, A. A. Klochikhin, J. Aderhold, J. Graul, O. Semchinova, and H. Harima, “Composition dependence of optical phonon energies and Raman line broadening in hexagonal AlxGa1–xN alloys,” Phys. Rev. B 65, 125203 (2002).
[Crossref]

Vogt, P.

T. Kolbe, A. Knauer, C. Chua, Z. Yang, S. Einfeldt, P. Vogt, N. M. Johnson, M. Weyers, and M. Kneissl, “Optical polarization characteristics of ultraviolet (In)(Al)GaN multiple quantum well light emitting diodes,” Appl. Phys. Lett. 97, 171105 (2010).
[Crossref]

Wan, H.

H. Hu, S. Zhou, H. Wan, X. Liu, N. Li, and H. Xu, “Effect of strain relaxation on performance of InGaN/GaN green LEDs grown on 4-inch sapphire substrate with sputtered AlN nucleation layer,” Sci. Rep. 9, 3447 (2019).
[Crossref]

Wan, Q.

S. Wang, J. Dai, J. Hu, S. Zhang, L. Xu, H. Long, J. Chen, Q. Wan, H.-C. Kuo, and C. Chen, “Ultrahigh degree of optical polarization above 80% in AlGaN-based deep-ultraviolet LED with moth-eye microstructure,” ACS Photon. 5, 3534–3540 (2018).
[Crossref]

Wang, J.

Y. Guo, Y. Zhang, J. Yan, H. Xie, L. Liu, X. Chen, M. Hou, Z. Qin, J. Wang, and J. Li, “Light extraction enhancement of AlGaN-based ultraviolet light-emitting diodes by substrate sidewall roughening,” Appl. Phys. Lett. 111, 011102 (2017).
[Crossref]

J. Yan, J. Wang, Y. Zhang, P. Cong, L. Sun, Y. Tian, C. Zhao, and J. Li, “AlGaN-based deep-ultraviolet light-emitting diodes grown on High-quality AlN template using MOVPE,” J. Cryst. Growth 414, 254–257 (2015).
[Crossref]

Wang, J. X.

Wang, S.

S. Wang, J. Dai, J. Hu, S. Zhang, L. Xu, H. Long, J. Chen, Q. Wan, H.-C. Kuo, and C. Chen, “Ultrahigh degree of optical polarization above 80% in AlGaN-based deep-ultraviolet LED with moth-eye microstructure,” ACS Photon. 5, 3534–3540 (2018).
[Crossref]

T. Detchprohm, Y.-S. Liu, K. Mehta, S. Wang, H. Xie, T.-T. Kao, S.-C. Shen, P. D. Yoder, F. A. Ponce, and R. D. Dupuis, “Sub 250  nm deep-UV AlGaN/AlN distributed Bragg reflectors,” Appl. Phys. Lett. 110, 011105 (2017).
[Crossref]

Wang, S.-C.

J.-I. Chyi, M.-H. Lo, Y. Nanishi, Y.-J. Cheng, H.-C. Kuo, H. Morkoç, J. Piprek, S.-C. Wang, and E. Yoon, “Fabrication and lasing characteristics of GaN nanopillars,” Proc. SPIE 7939, 79391T (2011).
[Crossref]

Wang, T. Y.

T. Y. Wang, C. T. Tasi, C. F. Lin, and D. S. Wuu, “85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering,” Sci. Rep. 7, 14422 (2017).
[Crossref]

Wang, X.

Wei, X. C.

Wernicke, T.

N. Susilo, S. Hagedorn, D. Jaeger, H. Miyake, U. Zeimer, C. Reich, B. Neuschulz, L. Sulmoni, M. Guttmann, F. Mehnke, C. Kuhn, T. Wernicke, M. Weyers, and M. Kneissl, “AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire,” Appl. Phys. Lett. 112, 041110 (2018).
[Crossref]

C. De Santi, M. Meneghini, D. Monti, J. Glaab, M. Guttmann, J. Rass, S. Einfeldt, F. Mehnke, J. Enslin, T. Wernicke, M. Kneissl, G. Meneghesso, and E. Zanoni, “Recombination mechanisms and thermal droop in AlGaN-based UV-B LEDs,” Photon. Res. 5, A44–A51 (2017).
[Crossref]

Weyers, M.

N. Susilo, S. Hagedorn, D. Jaeger, H. Miyake, U. Zeimer, C. Reich, B. Neuschulz, L. Sulmoni, M. Guttmann, F. Mehnke, C. Kuhn, T. Wernicke, M. Weyers, and M. Kneissl, “AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire,” Appl. Phys. Lett. 112, 041110 (2018).
[Crossref]

T. Kolbe, A. Knauer, C. Chua, Z. Yang, S. Einfeldt, P. Vogt, N. M. Johnson, M. Weyers, and M. Kneissl, “Optical polarization characteristics of ultraviolet (In)(Al)GaN multiple quantum well light emitting diodes,” Appl. Phys. Lett. 97, 171105 (2010).
[Crossref]

Wierer, J. J.

J. J. Wierer, A. A. Allerman, I. Montano, and M. W. Moseley, “Influence of optical polarization on the improvement of light extraction efficiency from reflective scattering structures in AlGaN ultraviolet light-emitting diodes,” Appl. Phys. Lett. 105, 061106 (2014).
[Crossref]

Wraback, M.

J. R. Grandusky, J. Chen, S. R. Gibb, M. C. Mendrick, C. G. Moe, L. Rodak, G. A. Garrett, M. Wraback, and L. J. Schowalter, “270  nm pseudomorphic ultraviolet light-emitting diodes with over 60  mW continuous wave output power,” Appl. Phys. Express 6, 032101 (2013).
[Crossref]

M. Shatalov, W. Sun, A. Lunev, X. Hu, A. Dobrinsky, Y. Bilenko, J. Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, and M. Wraback, “AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%,” Appl. Phys. Express 5, 082101 (2012).
[Crossref]

Wu, Q. Q.

Wunderer, T.

J. E. Northrup, C. L. Chua, Z. Yang, T. Wunderer, M. Kneissl, N. M. Johnson, and T. Kolbe, “Effect of strain and barrier composition on the polarization of light emission from AlGaN/AlN quantum wells,” Appl. Phys. Lett. 100, 021101 (2012).
[Crossref]

Wuu, D. S.

T. Y. Wang, C. T. Tasi, C. F. Lin, and D. S. Wuu, “85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering,” Sci. Rep. 7, 14422 (2017).
[Crossref]

Xiang, Y.

Xie, H.

T. Detchprohm, Y.-S. Liu, K. Mehta, S. Wang, H. Xie, T.-T. Kao, S.-C. Shen, P. D. Yoder, F. A. Ponce, and R. D. Dupuis, “Sub 250  nm deep-UV AlGaN/AlN distributed Bragg reflectors,” Appl. Phys. Lett. 110, 011105 (2017).
[Crossref]

Y. Guo, Y. Zhang, J. Yan, H. Xie, L. Liu, X. Chen, M. Hou, Z. Qin, J. Wang, and J. Li, “Light extraction enhancement of AlGaN-based ultraviolet light-emitting diodes by substrate sidewall roughening,” Appl. Phys. Lett. 111, 011102 (2017).
[Crossref]

Xing, H.

C. Liu, Y. K. Ooi, S. M. Islam, H. Xing, D. Jena, and J. Zhang, “234  nm and 246  nm AlN-Delta-GaN quantum well deep ultraviolet light-emitting diodes,” Appl. Phys. Lett. 112, 011101 (2018).
[Crossref]

Xiong, K.

G. Yuan, K. Xiong, C. Zhang, Y. Li, and J. Han, “Optical engineering of modal gain in a III-nitride laser with nanoporous GaN,” ACS Photon. 3, 1604–1610 (2016).
[Crossref]

Xu, H.

H. Hu, S. Zhou, H. Wan, X. Liu, N. Li, and H. Xu, “Effect of strain relaxation on performance of InGaN/GaN green LEDs grown on 4-inch sapphire substrate with sputtered AlN nucleation layer,” Sci. Rep. 9, 3447 (2019).
[Crossref]

Xu, L.

S. Wang, J. Dai, J. Hu, S. Zhang, L. Xu, H. Long, J. Chen, Q. Wan, H.-C. Kuo, and C. Chen, “Ultrahigh degree of optical polarization above 80% in AlGaN-based deep-ultraviolet LED with moth-eye microstructure,” ACS Photon. 5, 3534–3540 (2018).
[Crossref]

Yan, J.

Y. Guo, Y. Zhang, J. Yan, H. Xie, L. Liu, X. Chen, M. Hou, Z. Qin, J. Wang, and J. Li, “Light extraction enhancement of AlGaN-based ultraviolet light-emitting diodes by substrate sidewall roughening,” Appl. Phys. Lett. 111, 011102 (2017).
[Crossref]

J. Yan, J. Wang, Y. Zhang, P. Cong, L. Sun, Y. Tian, C. Zhao, and J. Li, “AlGaN-based deep-ultraviolet light-emitting diodes grown on High-quality AlN template using MOVPE,” J. Cryst. Growth 414, 254–257 (2015).
[Crossref]

Yan, J. C.

Yang, J.

M. Shatalov, W. Sun, A. Lunev, X. Hu, A. Dobrinsky, Y. Bilenko, J. Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, and M. Wraback, “AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%,” Appl. Phys. Express 5, 082101 (2012).
[Crossref]

Yang, S.-K.

P.-M. Tu, J.-R. Chang, S.-C. Huang, S.-K. Yang, Y.-W. Lin, T.-C. Hung, C.-P. Hsu, and C.-Y. Chang, “Investigation of efficiency droop for UV LED with N-type AlGaN layer,” Proc. SPIE 8278, 82781B (2012).
[Crossref]

Yang, Z.

J. E. Northrup, C. L. Chua, Z. Yang, T. Wunderer, M. Kneissl, N. M. Johnson, and T. Kolbe, “Effect of strain and barrier composition on the polarization of light emission from AlGaN/AlN quantum wells,” Appl. Phys. Lett. 100, 021101 (2012).
[Crossref]

T. Kolbe, A. Knauer, C. Chua, Z. Yang, S. Einfeldt, P. Vogt, N. M. Johnson, M. Weyers, and M. Kneissl, “Optical polarization characteristics of ultraviolet (In)(Al)GaN multiple quantum well light emitting diodes,” Appl. Phys. Lett. 97, 171105 (2010).
[Crossref]

Yoder, P. D.

T. Detchprohm, Y.-S. Liu, K. Mehta, S. Wang, H. Xie, T.-T. Kao, S.-C. Shen, P. D. Yoder, F. A. Ponce, and R. D. Dupuis, “Sub 250  nm deep-UV AlGaN/AlN distributed Bragg reflectors,” Appl. Phys. Lett. 110, 011105 (2017).
[Crossref]

Yoon, E.

J.-I. Chyi, M.-H. Lo, Y. Nanishi, Y.-J. Cheng, H.-C. Kuo, H. Morkoç, J. Piprek, S.-C. Wang, and E. Yoon, “Fabrication and lasing characteristics of GaN nanopillars,” Proc. SPIE 7939, 79391T (2011).
[Crossref]

Yu, T.

Yuan, G.

G. Yuan, K. Xiong, C. Zhang, Y. Li, and J. Han, “Optical engineering of modal gain in a III-nitride laser with nanoporous GaN,” ACS Photon. 3, 1604–1610 (2016).
[Crossref]

Zanoni, E.

Zeimer, U.

N. Susilo, S. Hagedorn, D. Jaeger, H. Miyake, U. Zeimer, C. Reich, B. Neuschulz, L. Sulmoni, M. Guttmann, F. Mehnke, C. Kuhn, T. Wernicke, M. Weyers, and M. Kneissl, “AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire,” Appl. Phys. Lett. 112, 041110 (2018).
[Crossref]

Zhang, C.

G. Yuan, K. Xiong, C. Zhang, Y. Li, and J. Han, “Optical engineering of modal gain in a III-nitride laser with nanoporous GaN,” ACS Photon. 3, 1604–1610 (2016).
[Crossref]

Zhang, J.

S. Tan, J. Zhang, T. Egawa, and G. Chen, “Influence of quantum-well number and an AlN electron blocking layer on the electroluminescence properties of AlGaN deep ultraviolet light-emitting diodes,” Appl. Sci. 8, 2402 (2018).
[Crossref]

C. Liu, Y. K. Ooi, S. M. Islam, H. Xing, D. Jena, and J. Zhang, “234  nm and 246  nm AlN-Delta-GaN quantum well deep ultraviolet light-emitting diodes,” Appl. Phys. Lett. 112, 011101 (2018).
[Crossref]

Zhang, L.

Zhang, S.

S. Wang, J. Dai, J. Hu, S. Zhang, L. Xu, H. Long, J. Chen, Q. Wan, H.-C. Kuo, and C. Chen, “Ultrahigh degree of optical polarization above 80% in AlGaN-based deep-ultraviolet LED with moth-eye microstructure,” ACS Photon. 5, 3534–3540 (2018).
[Crossref]

Zhang, Y.

Y. Zhang, R. Meng, Z.-H. Zhang, Q. Shi, L. Li, G. Liu, and W. Bi, “Effects of inclined sidewall structure with bottom metal air cavity on the light extraction efficiency for AlGaN-based deep ultraviolet light-emitting diodes,” IEEE Photon. J. 9, 1600709 (2017).
[Crossref]

Y. Guo, Y. Zhang, J. Yan, H. Xie, L. Liu, X. Chen, M. Hou, Z. Qin, J. Wang, and J. Li, “Light extraction enhancement of AlGaN-based ultraviolet light-emitting diodes by substrate sidewall roughening,” Appl. Phys. Lett. 111, 011102 (2017).
[Crossref]

J. Yan, J. Wang, Y. Zhang, P. Cong, L. Sun, Y. Tian, C. Zhao, and J. Li, “AlGaN-based deep-ultraviolet light-emitting diodes grown on High-quality AlN template using MOVPE,” J. Cryst. Growth 414, 254–257 (2015).
[Crossref]

Zhang, Z.-H.

Y. Zhang, R. Meng, Z.-H. Zhang, Q. Shi, L. Li, G. Liu, and W. Bi, “Effects of inclined sidewall structure with bottom metal air cavity on the light extraction efficiency for AlGaN-based deep ultraviolet light-emitting diodes,” IEEE Photon. J. 9, 1600709 (2017).
[Crossref]

Zhao, C.

J. Yan, J. Wang, Y. Zhang, P. Cong, L. Sun, Y. Tian, C. Zhao, and J. Li, “AlGaN-based deep-ultraviolet light-emitting diodes grown on High-quality AlN template using MOVPE,” J. Cryst. Growth 414, 254–257 (2015).
[Crossref]

Zhou, S.

H. Hu, S. Zhou, H. Wan, X. Liu, N. Li, and H. Xu, “Effect of strain relaxation on performance of InGaN/GaN green LEDs grown on 4-inch sapphire substrate with sputtered AlN nucleation layer,” Sci. Rep. 9, 3447 (2019).
[Crossref]

ACS Photon. (3)

S. Wang, J. Dai, J. Hu, S. Zhang, L. Xu, H. Long, J. Chen, Q. Wan, H.-C. Kuo, and C. Chen, “Ultrahigh degree of optical polarization above 80% in AlGaN-based deep-ultraviolet LED with moth-eye microstructure,” ACS Photon. 5, 3534–3540 (2018).
[Crossref]

J. W. Lee, J. H. Park, D. Y. Kim, E. F. Schubert, J. Kim, J. Lee, Y.-l. Kim, Y. Park, and J. K. Kim, “Arrays of truncated cone AlGaN deep-ultraviolet light-emitting diodes facilitating efficient outcoupling of in-plane emission,” ACS Photon. 3, 2030–2034 (2016).
[Crossref]

G. Yuan, K. Xiong, C. Zhang, Y. Li, and J. Han, “Optical engineering of modal gain in a III-nitride laser with nanoporous GaN,” ACS Photon. 3, 1604–1610 (2016).
[Crossref]

Appl. Phys. Express (4)

T. Takano, T. Mino, J. Sakai, N. Noguchi, K. Tsubaki, and H. Hirayama, “Deep-ultraviolet light-emitting diodes with external quantum efficiency higher than 20% at 275  nm achieved by improving light-extraction efficiency,” Appl. Phys. Express 10, 031002 (2017).
[Crossref]

J. R. Grandusky, J. Chen, S. R. Gibb, M. C. Mendrick, C. G. Moe, L. Rodak, G. A. Garrett, M. Wraback, and L. J. Schowalter, “270  nm pseudomorphic ultraviolet light-emitting diodes with over 60  mW continuous wave output power,” Appl. Phys. Express 6, 032101 (2013).
[Crossref]

H.-Y. Ryu, I.-G. Choi, H.-S. Choi, and J.-I. Shim, “Investigation of light extraction efficiency in AlGaN deep-ultraviolet light-emitting diodes,” Appl. Phys. Express 6, 062101 (2013).
[Crossref]

M. Shatalov, W. Sun, A. Lunev, X. Hu, A. Dobrinsky, Y. Bilenko, J. Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, and M. Wraback, “AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%,” Appl. Phys. Express 5, 082101 (2012).
[Crossref]

Appl. Phys. Lett. (13)

Y. Taniyasu and M. Kasu, “Surface 210  nm light emission from an AlN p-n junction light-emitting diode enhanced by A-plane growth orientation,” Appl. Phys. Lett. 96, 221110 (2010).
[Crossref]

J. E. Northrup, C. L. Chua, Z. Yang, T. Wunderer, M. Kneissl, N. M. Johnson, and T. Kolbe, “Effect of strain and barrier composition on the polarization of light emission from AlGaN/AlN quantum wells,” Appl. Phys. Lett. 100, 021101 (2012).
[Crossref]

C. Liu, Y. K. Ooi, S. M. Islam, H. Xing, D. Jena, and J. Zhang, “234  nm and 246  nm AlN-Delta-GaN quantum well deep ultraviolet light-emitting diodes,” Appl. Phys. Lett. 112, 011101 (2018).
[Crossref]

Z. Bryan, I. Bryan, S. Mita, J. Tweedie, Z. Sitar, and R. Collazo, “Strain dependence on polarization properties of AlGaN and AlGaN-based ultraviolet lasers grown on AlN substrates,” Appl. Phys. Lett. 106, 232101 (2015).
[Crossref]

T. Kolbe, A. Knauer, C. Chua, Z. Yang, S. Einfeldt, P. Vogt, N. M. Johnson, M. Weyers, and M. Kneissl, “Optical polarization characteristics of ultraviolet (In)(Al)GaN multiple quantum well light emitting diodes,” Appl. Phys. Lett. 97, 171105 (2010).
[Crossref]

K. B. Nam, J. Li, M. L. Nakarmi, J. Y. Lin, and H. X. Jiang, “Unique optical properties of AlGaN alloys and related ultraviolet emitters,” Appl. Phys. Lett. 84, 5264–5266 (2004).
[Crossref]

N. Susilo, S. Hagedorn, D. Jaeger, H. Miyake, U. Zeimer, C. Reich, B. Neuschulz, L. Sulmoni, M. Guttmann, F. Mehnke, C. Kuhn, T. Wernicke, M. Weyers, and M. Kneissl, “AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire,” Appl. Phys. Lett. 112, 041110 (2018).
[Crossref]

S. Inoue, Naoki, and M. Taniguchi, “150  mW deep-ultraviolet light-emitting diodes with large-area AlN nanophotonic light-extraction structure emitting at 265  nm,” Appl. Phys. Lett. 110, 141106 (2017).
[Crossref]

M. F. Schubert, S. Chhajed, J. K. Kim, E. F. Schubert, and J. Cho, “Polarization of light emission by 460  nm GaInN/GaN light-emitting diodes grown on (0001) oriented sapphire substrates,” Appl. Phys. Lett. 91, 051117 (2007).
[Crossref]

Y. Guo, Y. Zhang, J. Yan, H. Xie, L. Liu, X. Chen, M. Hou, Z. Qin, J. Wang, and J. Li, “Light extraction enhancement of AlGaN-based ultraviolet light-emitting diodes by substrate sidewall roughening,” Appl. Phys. Lett. 111, 011102 (2017).
[Crossref]

H. Hartono, C. B. Soh, S. Y. Chow, S. J. Chua, and E. A. Fitzgerald, “Reduction of threading dislocation density in GaN grown on strain relaxed nanoporous GaN template,” Appl. Phys. Lett. 90, 171917 (2007).
[Crossref]

T. Detchprohm, Y.-S. Liu, K. Mehta, S. Wang, H. Xie, T.-T. Kao, S.-C. Shen, P. D. Yoder, F. A. Ponce, and R. D. Dupuis, “Sub 250  nm deep-UV AlGaN/AlN distributed Bragg reflectors,” Appl. Phys. Lett. 110, 011105 (2017).
[Crossref]

J. J. Wierer, A. A. Allerman, I. Montano, and M. W. Moseley, “Influence of optical polarization on the improvement of light extraction efficiency from reflective scattering structures in AlGaN ultraviolet light-emitting diodes,” Appl. Phys. Lett. 105, 061106 (2014).
[Crossref]

Appl. Sci. (2)

Y. Nagasawa and A. Hirano, “A review of AlGaN-based deep-ultraviolet light-emitting diodes on sapphire,” Appl. Sci. 8, 1264 (2018).
[Crossref]

S. Tan, J. Zhang, T. Egawa, and G. Chen, “Influence of quantum-well number and an AlN electron blocking layer on the electroluminescence properties of AlGaN deep ultraviolet light-emitting diodes,” Appl. Sci. 8, 2402 (2018).
[Crossref]

IEEE Photon. J. (1)

Y. Zhang, R. Meng, Z.-H. Zhang, Q. Shi, L. Li, G. Liu, and W. Bi, “Effects of inclined sidewall structure with bottom metal air cavity on the light extraction efficiency for AlGaN-based deep ultraviolet light-emitting diodes,” IEEE Photon. J. 9, 1600709 (2017).
[Crossref]

J. Appl. Phys. (1)

A. Najar, M. Gerland, and M. Jouiad, “Porosity-induced relaxation of strains in GaN layers studied by means of micro-indentation and optical spectroscopy,” J. Appl. Phys. 111, 093513 (2012).
[Crossref]

J. Cryst. Growth (1)

J. Yan, J. Wang, Y. Zhang, P. Cong, L. Sun, Y. Tian, C. Zhao, and J. Li, “AlGaN-based deep-ultraviolet light-emitting diodes grown on High-quality AlN template using MOVPE,” J. Cryst. Growth 414, 254–257 (2015).
[Crossref]

Jpn. J. Appl. Phys. (2)

H. Hirayama, N. Maeda, S. Fujikawa, S. Toyoda, and N. Kamata, “Recent progress and future prospects of AlGaN-based high-efficiency deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys. 53, 100209 (2014).
[Crossref]

Y. Takashima, R. Shimizu, M. Haraguchi, and Y. Naoi, “Polarized emission characteristics of UV-LED with subwavelength grating,” Jpn. J. Appl. Phys. 53, 072101 (2014).
[Crossref]

Opt. Express (4)

Photon. Res. (1)

Phys. Rev. B (1)

V. Y. Davydov, I. N. Goncharuk, A. N. Smirnov, A. E. Nikolaev, W. V. Lundin, A. S. Usikov, A. A. Klochikhin, J. Aderhold, J. Graul, O. Semchinova, and H. Harima, “Composition dependence of optical phonon energies and Raman line broadening in hexagonal AlxGa1–xN alloys,” Phys. Rev. B 65, 125203 (2002).
[Crossref]

Phys. Status Solidi A (1)

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, 1176–1182 (2009).
[Crossref]

Proc. SPIE (2)

J.-I. Chyi, M.-H. Lo, Y. Nanishi, Y.-J. Cheng, H.-C. Kuo, H. Morkoç, J. Piprek, S.-C. Wang, and E. Yoon, “Fabrication and lasing characteristics of GaN nanopillars,” Proc. SPIE 7939, 79391T (2011).
[Crossref]

P.-M. Tu, J.-R. Chang, S.-C. Huang, S.-K. Yang, Y.-W. Lin, T.-C. Hung, C.-P. Hsu, and C.-Y. Chang, “Investigation of efficiency droop for UV LED with N-type AlGaN layer,” Proc. SPIE 8278, 82781B (2012).
[Crossref]

Sci. Rep. (3)

B. T. Tran, N. Maeda, M. Jo, D. Inoue, T. Kikitsu, and H. Hirayama, “Performance improvement of AlN crystal quality grown on patterned Si(111) substrate for deep UV-LED applications,” Sci. Rep. 6, 35681 (2016).
[Crossref]

T. Y. Wang, C. T. Tasi, C. F. Lin, and D. S. Wuu, “85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering,” Sci. Rep. 7, 14422 (2017).
[Crossref]

H. Hu, S. Zhou, H. Wan, X. Liu, N. Li, and H. Xu, “Effect of strain relaxation on performance of InGaN/GaN green LEDs grown on 4-inch sapphire substrate with sputtered AlN nucleation layer,” Sci. Rep. 9, 3447 (2019).
[Crossref]

Other (1)

J. Brodrick, M. Pattison, N. Bardsley, C. Elliot, M. Hansen, K. Lee, L. Pattison, J. Tsao, and M. Yamada, “2018 Solid-State Lighting R&D Opportunities,” DOE BTO SSL Program, DOE/EE-1907, https://www.energy.gov/sites/prod/files/2019/02/f59/edit.ssl_rd-opportunities_jan2019.pdf (2019).

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Figures (6)

Fig. 1.
Fig. 1. (a) Epitaxial structure of the scribed via holes and porous layer. (b) Cross-sectional view of the nanoporous n-AlGaN layer etched at 40 V. (c) SEM image of the cleaved region in the porous layer showing the subwavelength grating structure at higher magnification.
Fig. 2.
Fig. 2. (a) PL spectra of samples with different EC etching voltages. (b) Corrected PL enhancement ratio and average size of pore versus EC etching voltage.
Fig. 3.
Fig. 3. (a) Raman spectra of the etched samples and the reference sample measured at RT. (b) Raman shift (left) and PL peak wavelength (right) as a function of etching voltages.
Fig. 4.
Fig. 4. (a) Schematic diagram of the angular-dependent polarization PL measurement. (b) Far-field PL distribution in polar coordinates. (c) Enhancement ratio of samples etched at 60 V and 80 V as a function of θ.
Fig. 5.
Fig. 5. Angular-dependent PL intensity profile in the (a) TE and (b) TM mode; (c) the side-emitting PL spectra at different polarization angles: ψ=0°, ψ=90°, when θ=60°; (d) the integrated PL intensity against polarization angle ψ=0°360° of the reference unetched sample and 80 V etched sample, respectively.
Fig. 6.
Fig. 6. EL spectra and normalized EQE versus current of (a), (c) the 80 V etched sample compared to (b), (d) the reference sample. The inset of (a) shows the schematic of the porous LED.

Equations (5)

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I=ITEysin2θ+ITMcos2θ,
I=ITEx,
DOP=(TEtotalTMtotal)/(TEtotal+TMtotal),
TEtotal=ITEycos2θ+ITEx,
TMtotal=ITMsin2θ.