Abstract

An AlGaN quantum well (QW) structure of a deep-ultraviolet (UV) light-emitting diode (LED) needs to be well designed for controlling its band structure such that the heavy-hole (HH) band edge becomes lower than the split-off (SO) band edge and hence the transverse-electric (TE) polarization dominates the emission for achieving a higher light extraction efficiency. Here, we report the discovery of un-intentionally formed high-Al AlGaN nano-layers right above and below such a QW and their effects on the QW for changing the relative energy levels of the HH and SO bands. The comparison between the results of simulation study and polarization-resolved photoluminescence measurement confirms that the high-Al layers (HALs) represent the key to the observation of the dominating TE-polarized emission. By applying a stress onto a sample along its c-axis to produce a tensile strain in the c-plane for counteracting the HAL effects in changing the band structure, we can further understand the effectiveness of the HALs. The formation of the HALs is attributed to the hydrogen back-etching of Ga atoms during the temperature transition from quantum barrier growth into QW growth and vice versa. The Al filling in the etched vacancies results in the formation of an HAL. This discovery brings us with a simple method for enhancing the favored TE-polarized emission in an AlGaN deep-UV QW LED.

© 2017 Optical Society of America

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References

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  2. T. F. Kent, S. D. Carnevale, A. T. M. Sarwar, P. J. Phillips, R. F. Klie, and R. C. Myers, “Deep ultraviolet emitting polarization induced nanowire light emitting diodes with AlxGa1-xN active regions,” Nanotechnology 25(45), 455201 (2014).
    [PubMed]
  3. 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(8), 082101 (2012).
  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(3), 031002 (2017).
  5. H. Hirayama, Y. Tsukada, T. Maeda, and N. Kamata, “Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multiquantum-barrier electron blocking layer,” Appl. Phys. Express 3(3), 031002 (2010).
  6. 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(25), 5264–5266 (2004).
  7. 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(17), 171105 (2010).
  8. H. Kawanishia, M. Senuma, and T. Nukui, “Anisotropic polarization characteristics of lasing and spontaneous surface and edge emissions from deep-ultraviolet (λ≈240nm) AlGaN multiple-quantum-well lasers,” Appl. Phys. Lett. 89(4), 041126 (2006).
  9. 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(2), 021101 (2012).
  10. S. Fan, Z. Qin, C. He, X. Wang, B. Shen, and G. Zhang, “Strain effect on the optical polarization properties of c-plane Al0.26Ga0.74N/GaN superlattices,” Opt. Express 22(6), 6322–6328 (2014).
    [PubMed]
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  16. H. Hirayama, S. Fujikawa, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “Fabrication of a low threading dislocation density ELO-AlN template for application to deep-UV LEDs,” Phys. Status Solidi., C Curr. Top. Solid State Phys. 6(S2), S356–S359 (2009).
  17. 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(10), 100209 (2014).
  18. R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).
  19. T. Nishida, T. Makimoto, H. Saito, and T. Ban, “AlGaN-based ultraviolet light-emitting diodes grown on bulk AlN substrates,” Appl. Phys. Lett. 84(6), 1002–1003 (2004).
  20. T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).
  21. M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).
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    [PubMed]
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    [PubMed]
  24. J. Zhang, H. P. 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).
  25. X. J. Chen, T. J. Yu, H. M. Lu, G. C. Yuan, B. Shen, and G. Y. Zhang, “Modulating optical polarization properties of Al-rich AlGaN/AlN quantum well by controlling wavefunction overlap,” Appl. Phys. Lett. 103(18), 181117 (2013).
  26. Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).
  27. Z. H. Zhang, L. Li, Y. Zhang, F. Xu, Q. Shi, B. Shen, and W. Bi, “On the electric-field reservoir for III-nitride based deep ultraviolet light-emitting diodes,” Opt. Express 25(14), 16550–16559 (2017).
    [PubMed]
  28. S. Inoue, T. Naoki, T. Kinoshita, T. Obata, and H. Yanagi, “Light extraction enhancement of 265nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure,” Appl. Phys. Lett. 106(13), 131104 (2015).
  29. 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(1), 011102 (2017).
    [PubMed]
  30. M. K. Mahata, S. Ghosh, S. K. Jana, A. Chakraborty, A. Bag, P. Mukhopadhyay, R. Kumar, and D. Biswas, “Comprehensive strain and band gap analysis of PA-MBE grown AlGaN/GaN heterostructures on sapphire with ultra thin buffer,” AIP Adv. 4(11), 117120 (2014).
  31. The simulation program can be downloaded at http://yrwu-wk.ee.ntu.edu.tw/ .
  32. X. Chen, K. Y. Ho, and Y. R. Wu, “Modeling and optimization of p-AlGaN super lattice structure as the p-contact and transparent layer in AlGaN UVLEDs,” Opt. Express 23(25), 32367–32376 (2015).
    [PubMed]
  33. C. P. Wang and Y. R. Wu, “Study of optical anisotropy in nonpolar and semipolar AlGaN quantum well deep ultraviolet light emission diode,” J. Appl. Phys. 112(3), 033104 (2012).
  34. O. Ambacher, “Growth and applications of group III-nitrides,” J. Phys. D Appl. Phys. 31(20), 2653–2710 (1998).
  35. Y. T. Moon, Y. Fu, F. Yun, S. Dogan, M. Mikkelson, D. Johnstone, and H. Morkoç, “A study of GaN regrowth on the micro-facetted GaN template formed by in-situ thermal etching,” Phys. Status Solidi 202(5), 718–721 (2005).
  36. Y. Chen, H. Wu, E. Han, G. Yue, Z. Chen, Z. Wu, G. Wang, and H. Jiang, “High hole concentration in p-type AlGaN by indium-surfactant-assisted Mg-delta doping,” Appl. Phys. Lett. 106(16), 162102 (2015).
  37. C. Stampfl and C. G. Van de Walle, “Density-functional calculations for III-V nitrides using the local-density approximation and the generalized gradient approximation,” Phys. Rev. B 59(8), 5521–5535 (1999).
  38. 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).

2017 (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(3), 031002 (2017).

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

Z. H. Zhang, L. Li, Y. Zhang, F. Xu, Q. Shi, B. Shen, and W. Bi, “On the electric-field reservoir for III-nitride based deep ultraviolet light-emitting diodes,” Opt. Express 25(14), 16550–16559 (2017).
[PubMed]

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(1), 011102 (2017).
[PubMed]

2016 (1)

2015 (4)

S. Inoue, T. Naoki, T. Kinoshita, T. Obata, and H. Yanagi, “Light extraction enhancement of 265nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure,” Appl. Phys. Lett. 106(13), 131104 (2015).

X. Chen, K. Y. Ho, and Y. R. Wu, “Modeling and optimization of p-AlGaN super lattice structure as the p-contact and transparent layer in AlGaN UVLEDs,” Opt. Express 23(25), 32367–32376 (2015).
[PubMed]

Y. Chen, H. Wu, E. Han, G. Yue, Z. Chen, Z. Wu, G. Wang, and H. Jiang, “High hole concentration in p-type AlGaN by indium-surfactant-assisted Mg-delta doping,” Appl. Phys. Lett. 106(16), 162102 (2015).

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

2014 (5)

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(10), 100209 (2014).

S. Fan, Z. Qin, C. He, X. Wang, B. Shen, and G. Zhang, “Strain effect on the optical polarization properties of c-plane Al0.26Ga0.74N/GaN superlattices,” Opt. Express 22(6), 6322–6328 (2014).
[PubMed]

T. F. Kent, S. D. Carnevale, A. T. M. Sarwar, P. J. Phillips, R. F. Klie, and R. C. Myers, “Deep ultraviolet emitting polarization induced nanowire light emitting diodes with AlxGa1-xN active regions,” Nanotechnology 25(45), 455201 (2014).
[PubMed]

M. K. Mahata, S. Ghosh, S. K. Jana, A. Chakraborty, A. Bag, P. Mukhopadhyay, R. Kumar, and D. Biswas, “Comprehensive strain and band gap analysis of PA-MBE grown AlGaN/GaN heterostructures on sapphire with ultra thin buffer,” AIP Adv. 4(11), 117120 (2014).

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

2013 (2)

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

X. J. Chen, T. J. Yu, H. M. Lu, G. C. Yuan, B. Shen, and G. Y. Zhang, “Modulating optical polarization properties of Al-rich AlGaN/AlN quantum well by controlling wavefunction overlap,” Appl. Phys. Lett. 103(18), 181117 (2013).

2012 (4)

H. Lu, T. Yu, G. Yuan, X. Chen, Z. Chen, G. Chen, and G. Zhang, “Enhancement of surface emission in deep ultraviolet AlGaN-based light emitting diodes with staggered quantum wells,” Opt. Lett. 37(17), 3693–3695 (2012).
[PubMed]

C. P. Wang and Y. R. Wu, “Study of optical anisotropy in nonpolar and semipolar AlGaN quantum well deep ultraviolet light emission diode,” J. Appl. Phys. 112(3), 033104 (2012).

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(8), 082101 (2012).

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(2), 021101 (2012).

2011 (2)

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

J. Zhang, H. P. 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).

2010 (2)

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(17), 171105 (2010).

H. Hirayama, Y. Tsukada, T. Maeda, and N. Kamata, “Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multiquantum-barrier electron blocking layer,” Appl. Phys. Express 3(3), 031002 (2010).

2009 (1)

H. Hirayama, S. Fujikawa, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “Fabrication of a low threading dislocation density ELO-AlN template for application to deep-UV LEDs,” Phys. Status Solidi., C Curr. Top. Solid State Phys. 6(S2), S356–S359 (2009).

2007 (2)

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

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).

2006 (1)

H. Kawanishia, M. Senuma, and T. Nukui, “Anisotropic polarization characteristics of lasing and spontaneous surface and edge emissions from deep-ultraviolet (λ≈240nm) AlGaN multiple-quantum-well lasers,” Appl. Phys. Lett. 89(4), 041126 (2006).

2005 (1)

Y. T. Moon, Y. Fu, F. Yun, S. Dogan, M. Mikkelson, D. Johnstone, and H. Morkoç, “A study of GaN regrowth on the micro-facetted GaN template formed by in-situ thermal etching,” Phys. Status Solidi 202(5), 718–721 (2005).

2004 (2)

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(25), 5264–5266 (2004).

T. Nishida, T. Makimoto, H. Saito, and T. Ban, “AlGaN-based ultraviolet light-emitting diodes grown on bulk AlN substrates,” Appl. Phys. Lett. 84(6), 1002–1003 (2004).

2003 (1)

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

2002 (1)

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

1999 (1)

C. Stampfl and C. G. Van de Walle, “Density-functional calculations for III-V nitrides using the local-density approximation and the generalized gradient approximation,” Phys. Rev. B 59(8), 5521–5535 (1999).

1998 (1)

O. Ambacher, “Growth and applications of group III-nitrides,” J. Phys. D Appl. Phys. 31(20), 2653–2710 (1998).

1997 (1)

S. L. Chuang and C. S. Chang, “A band-structure model of strained quantum-well wurtzite semiconductors,” Semicond. Sci. Technol. 12(3), 252–263 (1997).

1996 (1)

S. L. Chuang and C. S. Chang, “k·p method for strained wurtzite semiconductors,” Phys. Rev. B 54(4), 2491–2504 (1996).

Akasaki, I.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Amano, H.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Ambacher, O.

O. Ambacher, “Growth and applications of group III-nitrides,” J. Phys. D Appl. Phys. 31(20), 2653–2710 (1998).

Bag, A.

M. K. Mahata, S. Ghosh, S. K. Jana, A. Chakraborty, A. Bag, P. Mukhopadhyay, R. Kumar, and D. Biswas, “Comprehensive strain and band gap analysis of PA-MBE grown AlGaN/GaN heterostructures on sapphire with ultra thin buffer,” AIP Adv. 4(11), 117120 (2014).

Balakrishnan, K.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Ban, T.

T. Nishida, T. Makimoto, H. Saito, and T. Ban, “AlGaN-based ultraviolet light-emitting diodes grown on bulk AlN substrates,” Appl. Phys. Lett. 84(6), 1002–1003 (2004).

Bandoh, A.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Bi, W.

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

Z. H. Zhang, L. Li, Y. Zhang, F. Xu, Q. Shi, B. Shen, and W. Bi, “On the electric-field reservoir for III-nitride based deep ultraviolet light-emitting diodes,” Opt. Express 25(14), 16550–16559 (2017).
[PubMed]

Bickermann, M.

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

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(8), 082101 (2012).

Biswas, D.

M. K. Mahata, S. Ghosh, S. K. Jana, A. Chakraborty, A. Bag, P. Mukhopadhyay, R. Kumar, and D. Biswas, “Comprehensive strain and band gap analysis of PA-MBE grown AlGaN/GaN heterostructures on sapphire with ultra thin buffer,” AIP Adv. 4(11), 117120 (2014).

Carnevale, S. D.

T. F. Kent, S. D. Carnevale, A. T. M. Sarwar, P. J. Phillips, R. F. Klie, and R. C. Myers, “Deep ultraviolet emitting polarization induced nanowire light emitting diodes with AlxGa1-xN active regions,” Nanotechnology 25(45), 455201 (2014).
[PubMed]

Chakraborty, A.

M. K. Mahata, S. Ghosh, S. K. Jana, A. Chakraborty, A. Bag, P. Mukhopadhyay, R. Kumar, and D. Biswas, “Comprehensive strain and band gap analysis of PA-MBE grown AlGaN/GaN heterostructures on sapphire with ultra thin buffer,” AIP Adv. 4(11), 117120 (2014).

Chang, C. S.

S. L. Chuang and C. S. Chang, “A band-structure model of strained quantum-well wurtzite semiconductors,” Semicond. Sci. Technol. 12(3), 252–263 (1997).

S. L. Chuang and C. S. Chang, “k·p method for strained wurtzite semiconductors,” Phys. Rev. B 54(4), 2491–2504 (1996).

Chen, C.

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

Chen, G.

Chen, X.

Chen, X. J.

X. J. Chen, T. J. Yu, H. M. Lu, G. C. Yuan, B. Shen, and G. Y. Zhang, “Modulating optical polarization properties of Al-rich AlGaN/AlN quantum well by controlling wavefunction overlap,” Appl. Phys. Lett. 103(18), 181117 (2013).

Chen, Y.

Y. Chen, H. Wu, E. Han, G. Yue, Z. Chen, Z. Wu, G. Wang, and H. Jiang, “High hole concentration in p-type AlGaN by indium-surfactant-assisted Mg-delta doping,” Appl. Phys. Lett. 106(16), 162102 (2015).

Chen, Z.

Y. Chen, H. Wu, E. Han, G. Yue, Z. Chen, Z. Wu, G. Wang, and H. Jiang, “High hole concentration in p-type AlGaN by indium-surfactant-assisted Mg-delta doping,” Appl. Phys. Lett. 106(16), 162102 (2015).

H. Lu, T. Yu, G. Yuan, X. Chen, Z. Chen, G. Chen, and G. Zhang, “Enhancement of surface emission in deep ultraviolet AlGaN-based light emitting diodes with staggered quantum wells,” Opt. Lett. 37(17), 3693–3695 (2012).
[PubMed]

Chu, C.

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

Chua, C.

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

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(17), 171105 (2010).

Chua, C. L.

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(2), 021101 (2012).

Chuang, S. L.

S. L. Chuang and C. S. Chang, “A band-structure model of strained quantum-well wurtzite semiconductors,” Semicond. Sci. Technol. 12(3), 252–263 (1997).

S. L. Chuang and C. S. Chang, “k·p method for strained wurtzite semiconductors,” Phys. Rev. B 54(4), 2491–2504 (1996).

Dobrinsky, A.

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(8), 082101 (2012).

Dogan, S.

Y. T. Moon, Y. Fu, F. Yun, S. Dogan, M. Mikkelson, D. Johnstone, and H. Morkoç, “A study of GaN regrowth on the micro-facetted GaN template formed by in-situ thermal etching,” Phys. Status Solidi 202(5), 718–721 (2005).

Einfeldt, S.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

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(17), 171105 (2010).

Fan, S.

Fang, M.

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

Feneberg, M.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

Fu, L.

Fu, Y.

Y. T. Moon, Y. Fu, F. Yun, S. Dogan, M. Mikkelson, D. Johnstone, and H. Morkoç, “A study of GaN regrowth on the micro-facetted GaN template formed by in-situ thermal etching,” Phys. Status Solidi 202(5), 718–721 (2005).

Fujikawa, 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(10), 100209 (2014).

H. Hirayama, S. Fujikawa, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “Fabrication of a low threading dislocation density ELO-AlN template for application to deep-UV LEDs,” Phys. Status Solidi., C Curr. Top. Solid State Phys. 6(S2), S356–S359 (2009).

Fujimoto, N.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Garrett, G.

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(8), 082101 (2012).

Gaska, R.

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(8), 082101 (2012).

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

Ge, W.

Ghosh, S.

M. K. Mahata, S. Ghosh, S. K. Jana, A. Chakraborty, A. Bag, P. Mukhopadhyay, R. Kumar, and D. Biswas, “Comprehensive strain and band gap analysis of PA-MBE grown AlGaN/GaN heterostructures on sapphire with ultra thin buffer,” AIP Adv. 4(11), 117120 (2014).

Goldhahn, R.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

Guo, Y.

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(1), 011102 (2017).
[PubMed]

Guttmann, M.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

Han, E.

Y. Chen, H. Wu, E. Han, G. Yue, Z. Chen, Z. Wu, G. Wang, and H. Jiang, “High hole concentration in p-type AlGaN by indium-surfactant-assisted Mg-delta doping,” Appl. Phys. Lett. 106(16), 162102 (2015).

Hartmann, C.

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

He, C.

Hirayama, H.

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(3), 031002 (2017).

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(10), 100209 (2014).

H. Hirayama, Y. Tsukada, T. Maeda, and N. Kamata, “Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multiquantum-barrier electron blocking layer,” Appl. Phys. Express 3(3), 031002 (2010).

H. Hirayama, S. Fujikawa, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “Fabrication of a low threading dislocation density ELO-AlN template for application to deep-UV LEDs,” Phys. Status Solidi., C Curr. Top. Solid State Phys. 6(S2), S356–S359 (2009).

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).

Ho, K. Y.

Hou, M.

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(1), 011102 (2017).
[PubMed]

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(8), 082101 (2012).

Huang Chen, S. W.

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

Imura, M.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Inoue, S.

S. Inoue, T. Naoki, T. Kinoshita, T. Obata, and H. Yanagi, “Light extraction enhancement of 265nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure,” Appl. Phys. Lett. 106(13), 131104 (2015).

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

Iwaya, M.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Jana, S. K.

M. K. Mahata, S. Ghosh, S. K. Jana, A. Chakraborty, A. Bag, P. Mukhopadhyay, R. Kumar, and D. Biswas, “Comprehensive strain and band gap analysis of PA-MBE grown AlGaN/GaN heterostructures on sapphire with ultra thin buffer,” AIP Adv. 4(11), 117120 (2014).

Jiang, H.

Y. Chen, H. Wu, E. Han, G. Yue, Z. Chen, Z. Wu, G. Wang, and H. Jiang, “High hole concentration in p-type AlGaN by indium-surfactant-assisted Mg-delta doping,” Appl. Phys. Lett. 106(16), 162102 (2015).

Jiang, H. X.

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(25), 5264–5266 (2004).

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(2), 021101 (2012).

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(17), 171105 (2010).

Johnstone, D.

Y. T. Moon, Y. Fu, F. Yun, S. Dogan, M. Mikkelson, D. Johnstone, and H. Morkoç, “A study of GaN regrowth on the micro-facetted GaN template formed by in-situ thermal etching,” Phys. Status Solidi 202(5), 718–721 (2005).

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(10), 100209 (2014).

H. Hirayama, Y. Tsukada, T. Maeda, and N. Kamata, “Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multiquantum-barrier electron blocking layer,” Appl. Phys. Express 3(3), 031002 (2010).

H. Hirayama, S. Fujikawa, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “Fabrication of a low threading dislocation density ELO-AlN template for application to deep-UV LEDs,” Phys. Status Solidi., C Curr. Top. Solid State Phys. 6(S2), S356–S359 (2009).

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).

Kamiyama, S.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Kawanishia, H.

H. Kawanishia, M. Senuma, and T. Nukui, “Anisotropic polarization characteristics of lasing and spontaneous surface and edge emissions from deep-ultraviolet (λ≈240nm) AlGaN multiple-quantum-well lasers,” Appl. Phys. Lett. 89(4), 041126 (2006).

Kent, T. F.

T. F. Kent, S. D. Carnevale, A. T. M. Sarwar, P. J. Phillips, R. F. Klie, and R. C. Myers, “Deep ultraviolet emitting polarization induced nanowire light emitting diodes with AlxGa1-xN active regions,” Nanotechnology 25(45), 455201 (2014).
[PubMed]

Khan, A.

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

Kinoshita, T.

S. Inoue, T. Naoki, T. Kinoshita, T. Obata, and H. Yanagi, “Light extraction enhancement of 265nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure,” Appl. Phys. Lett. 106(13), 131104 (2015).

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

Klie, R. F.

T. F. Kent, S. D. Carnevale, A. T. M. Sarwar, P. J. Phillips, R. F. Klie, and R. C. Myers, “Deep ultraviolet emitting polarization induced nanowire light emitting diodes with AlxGa1-xN active regions,” Nanotechnology 25(45), 455201 (2014).
[PubMed]

Knauer, A.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

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(17), 171105 (2010).

Kneissl, M.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

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(2), 021101 (2012).

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

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(17), 171105 (2010).

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(2), 021101 (2012).

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

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(17), 171105 (2010).

Koukitu, A.

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

Kueller, V.

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

Kuhn, C.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

Kuller, V.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

Kumagai, Y.

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

Kumar, R.

M. K. Mahata, S. Ghosh, S. K. Jana, A. Chakraborty, A. Bag, P. Mukhopadhyay, R. Kumar, and D. Biswas, “Comprehensive strain and band gap analysis of PA-MBE grown AlGaN/GaN heterostructures on sapphire with ultra thin buffer,” AIP Adv. 4(11), 117120 (2014).

Kuo, H. C.

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

Kuokstis, E.

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

Lapeyrade, M.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

Li, 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(1), 011102 (2017).
[PubMed]

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(25), 5264–5266 (2004).

Li, L.

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

Z. H. Zhang, L. Li, Y. Zhang, F. Xu, Q. Shi, B. Shen, and W. Bi, “On the electric-field reservoir for III-nitride based deep ultraviolet light-emitting diodes,” Opt. Express 25(14), 16550–16559 (2017).
[PubMed]

Lin, J. Y.

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(25), 5264–5266 (2004).

Liu, L.

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(1), 011102 (2017).
[PubMed]

Lobo, N.

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

Lu, H.

Lu, H. M.

X. J. Chen, T. J. Yu, H. M. Lu, G. C. Yuan, B. Shen, and G. Y. Zhang, “Modulating optical polarization properties of Al-rich AlGaN/AlN quantum well by controlling wavefunction overlap,” Appl. Phys. Lett. 103(18), 181117 (2013).

Lunev, A.

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(8), 082101 (2012).

Maeda, 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(10), 100209 (2014).

Maeda, T.

H. Hirayama, Y. Tsukada, T. Maeda, and N. Kamata, “Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multiquantum-barrier electron blocking layer,” Appl. Phys. Express 3(3), 031002 (2010).

Mahata, M. K.

M. K. Mahata, S. Ghosh, S. K. Jana, A. Chakraborty, A. Bag, P. Mukhopadhyay, R. Kumar, and D. Biswas, “Comprehensive strain and band gap analysis of PA-MBE grown AlGaN/GaN heterostructures on sapphire with ultra thin buffer,” AIP Adv. 4(11), 117120 (2014).

Makimoto, T.

T. Nishida, T. Makimoto, H. Saito, and T. Ban, “AlGaN-based ultraviolet light-emitting diodes grown on bulk AlN substrates,” Appl. Phys. Lett. 84(6), 1002–1003 (2004).

Martens, M.

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

Mehnke, F.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

Meyer, J. R.

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

Mikkelson, M.

Y. T. Moon, Y. Fu, F. Yun, S. Dogan, M. Mikkelson, D. Johnstone, and H. Morkoç, “A study of GaN regrowth on the micro-facetted GaN template formed by in-situ thermal etching,” Phys. Status Solidi 202(5), 718–721 (2005).

Mino, T.

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(3), 031002 (2017).

Mita, S.

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

Moe, C.

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(8), 082101 (2012).

Moody, B.

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

Moon, Y. T.

Y. T. Moon, Y. Fu, F. Yun, S. Dogan, M. Mikkelson, D. Johnstone, and H. Morkoç, “A study of GaN regrowth on the micro-facetted GaN template formed by in-situ thermal etching,” Phys. Status Solidi 202(5), 718–721 (2005).

Morkoç, H.

Y. T. Moon, Y. Fu, F. Yun, S. Dogan, M. Mikkelson, D. Johnstone, and H. Morkoç, “A study of GaN regrowth on the micro-facetted GaN template formed by in-situ thermal etching,” Phys. Status Solidi 202(5), 718–721 (2005).

Mukhopadhyay, P.

M. K. Mahata, S. Ghosh, S. K. Jana, A. Chakraborty, A. Bag, P. Mukhopadhyay, R. Kumar, and D. Biswas, “Comprehensive strain and band gap analysis of PA-MBE grown AlGaN/GaN heterostructures on sapphire with ultra thin buffer,” AIP Adv. 4(11), 117120 (2014).

Myers, R. C.

T. F. Kent, S. D. Carnevale, A. T. M. Sarwar, P. J. Phillips, R. F. Klie, and R. C. Myers, “Deep ultraviolet emitting polarization induced nanowire light emitting diodes with AlxGa1-xN active regions,” Nanotechnology 25(45), 455201 (2014).
[PubMed]

Nagashima, T.

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

Nakano, K.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Nakarmi, M. L.

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(25), 5264–5266 (2004).

Nam, K. B.

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(25), 5264–5266 (2004).

Naoki, T.

S. Inoue, T. Naoki, T. Kinoshita, T. Obata, and H. Yanagi, “Light extraction enhancement of 265nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure,” Appl. Phys. Lett. 106(13), 131104 (2015).

Narita, G.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Netzel, C.

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

Nishida, T.

T. Nishida, T. Makimoto, H. Saito, and T. Ban, “AlGaN-based ultraviolet light-emitting diodes grown on bulk AlN substrates,” Appl. Phys. Lett. 84(6), 1002–1003 (2004).

Noguchi, N.

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(3), 031002 (2017).

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).

Norimatsu, J.

H. Hirayama, S. Fujikawa, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “Fabrication of a low threading dislocation density ELO-AlN template for application to deep-UV LEDs,” Phys. Status Solidi., C Curr. Top. Solid State Phys. 6(S2), S356–S359 (2009).

Noro, T.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Northrup, J. E.

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(2), 021101 (2012).

Nukui, T.

H. Kawanishia, M. Senuma, and T. Nukui, “Anisotropic polarization characteristics of lasing and spontaneous surface and edge emissions from deep-ultraviolet (λ≈240nm) AlGaN multiple-quantum-well lasers,” Appl. Phys. Lett. 89(4), 041126 (2006).

Obata, T.

S. Inoue, T. Naoki, T. Kinoshita, T. Obata, and H. Yanagi, “Light extraction enhancement of 265nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure,” Appl. Phys. Lett. 106(13), 131104 (2015).

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

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).

Okada, N.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Phillips, P. J.

T. F. Kent, S. D. Carnevale, A. T. M. Sarwar, P. J. Phillips, R. F. Klie, and R. C. Myers, “Deep ultraviolet emitting polarization induced nanowire light emitting diodes with AlxGa1-xN active regions,” Nanotechnology 25(45), 455201 (2014).
[PubMed]

Qin, Z.

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(1), 011102 (2017).
[PubMed]

S. Fan, Z. Qin, C. He, X. Wang, B. Shen, and G. Zhang, “Strain effect on the optical polarization properties of c-plane Al0.26Ga0.74N/GaN superlattices,” Opt. Express 22(6), 6322–6328 (2014).
[PubMed]

Rass, H.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

Rass, J.

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

Reich, C.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

Rodriguez, H.

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

Rojo, J. C.

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

Saito, H.

T. Nishida, T. Makimoto, H. Saito, and T. Ban, “AlGaN-based ultraviolet light-emitting diodes grown on bulk AlN substrates,” Appl. Phys. Lett. 84(6), 1002–1003 (2004).

Sakai, J.

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(3), 031002 (2017).

Sarwar, A. T. M.

T. F. Kent, S. D. Carnevale, A. T. M. Sarwar, P. J. Phillips, R. F. Klie, and R. C. Myers, “Deep ultraviolet emitting polarization induced nanowire light emitting diodes with AlxGa1-xN active regions,” Nanotechnology 25(45), 455201 (2014).
[PubMed]

Schowalter, L. J.

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

Senuma, M.

H. Kawanishia, M. Senuma, and T. Nukui, “Anisotropic polarization characteristics of lasing and spontaneous surface and edge emissions from deep-ultraviolet (λ≈240nm) AlGaN multiple-quantum-well lasers,” Appl. Phys. Lett. 89(4), 041126 (2006).

Shatalov, M.

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(8), 082101 (2012).

Shen, B.

Shi, Q.

Shur, M.

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(8), 082101 (2012).

Shur, M. S.

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

Sitar, Z.

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

Stampfl, C.

C. Stampfl and C. G. Van de Walle, “Density-functional calculations for III-V nitrides using the local-density approximation and the generalized gradient approximation,” Phys. Rev. B 59(8), 5521–5535 (1999).

Stellmach, J.

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

Sun, W.

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(8), 082101 (2012).

Takagi, T.

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

Takano, T.

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(3), 031002 (2017).

H. Hirayama, S. Fujikawa, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “Fabrication of a low threading dislocation density ELO-AlN template for application to deep-UV LEDs,” Phys. Status Solidi., C Curr. Top. Solid State Phys. 6(S2), S356–S359 (2009).

Tamulaitis, G.

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

Tang, N.

Tansu, N.

J. Zhang, H. P. 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).

Tian, K.

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

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(10), 100209 (2014).

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(3), 031002 (2017).

H. Hirayama, S. Fujikawa, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “Fabrication of a low threading dislocation density ELO-AlN template for application to deep-UV LEDs,” Phys. Status Solidi., C Curr. Top. Solid State Phys. 6(S2), S356–S359 (2009).

Tsukada, Y.

H. Hirayama, Y. Tsukada, T. Maeda, and N. Kamata, “Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multiquantum-barrier electron blocking layer,” Appl. Phys. Express 3(3), 031002 (2010).

Van de Walle, C. G.

C. Stampfl and C. G. Van de Walle, “Density-functional calculations for III-V nitrides using the local-density approximation and the generalized gradient approximation,” Phys. Rev. B 59(8), 5521–5535 (1999).

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(17), 171105 (2010).

Vurgaftman, I.

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

Wang, C. P.

C. P. Wang and Y. R. Wu, “Study of optical anisotropy in nonpolar and semipolar AlGaN quantum well deep ultraviolet light emission diode,” J. Appl. Phys. 112(3), 033104 (2012).

Wang, G.

Y. Chen, H. Wu, E. Han, G. Yue, Z. Chen, Z. Wu, G. Wang, and H. Jiang, “High hole concentration in p-type AlGaN by indium-surfactant-assisted Mg-delta doping,” Appl. Phys. Lett. 106(16), 162102 (2015).

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(1), 011102 (2017).
[PubMed]

Wang, M.

Wang, S. W.

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

Wang, W.

Wang, X.

Wernicke, T.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

Weyers, M.

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

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(17), 171105 (2010).

Wollweber, J.

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

Wraback, M.

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(8), 082101 (2012).

Wu, H.

Y. Chen, H. Wu, E. Han, G. Yue, Z. Chen, Z. Wu, G. Wang, and H. Jiang, “High hole concentration in p-type AlGaN by indium-surfactant-assisted Mg-delta doping,” Appl. Phys. Lett. 106(16), 162102 (2015).

Wu, Y. R.

X. Chen, K. Y. Ho, and Y. R. Wu, “Modeling and optimization of p-AlGaN super lattice structure as the p-contact and transparent layer in AlGaN UVLEDs,” Opt. Express 23(25), 32367–32376 (2015).
[PubMed]

C. P. Wang and Y. R. Wu, “Study of optical anisotropy in nonpolar and semipolar AlGaN quantum well deep ultraviolet light emission diode,” J. Appl. Phys. 112(3), 033104 (2012).

Wu, Z.

Y. Chen, H. Wu, E. Han, G. Yue, Z. Chen, Z. Wu, G. Wang, and H. Jiang, “High hole concentration in p-type AlGaN by indium-surfactant-assisted Mg-delta doping,” Appl. Phys. Lett. 106(16), 162102 (2015).

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(2), 021101 (2012).

Xie, H.

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(1), 011102 (2017).
[PubMed]

Xu, F.

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(1), 011102 (2017).
[PubMed]

Yanagi, H.

S. Inoue, T. Naoki, T. Kinoshita, T. Obata, and H. Yanagi, “Light extraction enhancement of 265nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure,” Appl. Phys. Lett. 106(13), 131104 (2015).

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

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(8), 082101 (2012).

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

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(2), 021101 (2012).

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

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(17), 171105 (2010).

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).

Yilmaz, I.

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

Yu, T.

Yu, T. J.

X. J. Chen, T. J. Yu, H. M. Lu, G. C. Yuan, B. Shen, and G. Y. Zhang, “Modulating optical polarization properties of Al-rich AlGaN/AlN quantum well by controlling wavefunction overlap,” Appl. Phys. Lett. 103(18), 181117 (2013).

Yuan, G.

Yuan, G. C.

X. J. Chen, T. J. Yu, H. M. Lu, G. C. Yuan, B. Shen, and G. Y. Zhang, “Modulating optical polarization properties of Al-rich AlGaN/AlN quantum well by controlling wavefunction overlap,” Appl. Phys. Lett. 103(18), 181117 (2013).

Yue, G.

Y. Chen, H. Wu, E. Han, G. Yue, Z. Chen, Z. Wu, G. Wang, and H. Jiang, “High hole concentration in p-type AlGaN by indium-surfactant-assisted Mg-delta doping,” Appl. Phys. Lett. 106(16), 162102 (2015).

Yun, F.

Y. T. Moon, Y. Fu, F. Yun, S. Dogan, M. Mikkelson, D. Johnstone, and H. Morkoç, “A study of GaN regrowth on the micro-facetted GaN template formed by in-situ thermal etching,” Phys. Status Solidi 202(5), 718–721 (2005).

Zhang, G.

Zhang, G. Y.

X. J. Chen, T. J. Yu, H. M. Lu, G. C. Yuan, B. Shen, and G. Y. Zhang, “Modulating optical polarization properties of Al-rich AlGaN/AlN quantum well by controlling wavefunction overlap,” Appl. Phys. Lett. 103(18), 181117 (2013).

Zhang, J.

J. Zhang, H. P. 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).

Zhang, Y.

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

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(1), 011102 (2017).
[PubMed]

Z. H. Zhang, L. Li, Y. Zhang, F. Xu, Q. Shi, B. Shen, and W. Bi, “On the electric-field reservoir for III-nitride based deep ultraviolet light-emitting diodes,” Opt. Express 25(14), 16550–16559 (2017).
[PubMed]

Zhang, Z. H.

Z. H. Zhang, L. Li, Y. Zhang, F. Xu, Q. Shi, B. Shen, and W. Bi, “On the electric-field reservoir for III-nitride based deep ultraviolet light-emitting diodes,” Opt. Express 25(14), 16550–16559 (2017).
[PubMed]

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

Zhao, H. P.

J. Zhang, H. P. 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).

ACS Photonics (1)

Z. H. Zhang, S. W. Huang Chen, Y. Zhang, L. Li, S. W. Wang, K. Tian, C. Chu, M. Fang, H. C. Kuo, and W. Bi, “Hole transport manipulation to improve the hole injection for deep ultraviolet light-emitting diodes,” ACS Photonics 4(7), 1846–1850 (2017).

AIP Adv. (1)

M. K. Mahata, S. Ghosh, S. K. Jana, A. Chakraborty, A. Bag, P. Mukhopadhyay, R. Kumar, and D. Biswas, “Comprehensive strain and band gap analysis of PA-MBE grown AlGaN/GaN heterostructures on sapphire with ultra thin buffer,” AIP Adv. 4(11), 117120 (2014).

Appl. Phys. Express (4)

T. Kinoshita, T. Obata, T. Nagashima, H. Yanagi, B. Moody, S. Mita, S. Inoue, Y. Kumagai, A. Koukitu, and Z. Sitar, “Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy,” Appl. Phys. Express 6(9), 092103 (2013).

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(8), 082101 (2012).

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(3), 031002 (2017).

H. Hirayama, Y. Tsukada, T. Maeda, and N. Kamata, “Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multiquantum-barrier electron blocking layer,” Appl. Phys. Express 3(3), 031002 (2010).

Appl. Phys. Lett. (13)

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(25), 5264–5266 (2004).

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(17), 171105 (2010).

H. Kawanishia, M. Senuma, and T. Nukui, “Anisotropic polarization characteristics of lasing and spontaneous surface and edge emissions from deep-ultraviolet (λ≈240nm) AlGaN multiple-quantum-well lasers,” Appl. Phys. Lett. 89(4), 041126 (2006).

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(2), 021101 (2012).

C. Reich, M. Guttmann, M. Feneberg, T. Wernicke, F. Mehnke, C. Kuhn, H. Rass, M. Lapeyrade, S. Einfeldt, A. Knauer, V. Kuller, M. Weyers, R. Goldhahn, and M. Kneissl, “Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes,” Appl. Phys. Lett. 107(14), 142101 (2015).

R. Gaska, C. Chen, J. Yang, E. Kuokstis, A. Khan, G. Tamulaitis, I. Yilmaz, M. S. Shur, J. C. Rojo, and L. J. Schowalter, “Deep-ultraviolet emission of AlGaN/AlN quantum wells on bulk AlN,” Appl. Phys. Lett. 81(24), 4658–4660 (2002).

T. Nishida, T. Makimoto, H. Saito, and T. Ban, “AlGaN-based ultraviolet light-emitting diodes grown on bulk AlN substrates,” Appl. Phys. Lett. 84(6), 1002–1003 (2004).

J. Zhang, H. P. 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).

X. J. Chen, T. J. Yu, H. M. Lu, G. C. Yuan, B. Shen, and G. Y. Zhang, “Modulating optical polarization properties of Al-rich AlGaN/AlN quantum well by controlling wavefunction overlap,” Appl. Phys. Lett. 103(18), 181117 (2013).

S. Inoue, T. Naoki, T. Kinoshita, T. Obata, and H. Yanagi, “Light extraction enhancement of 265nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure,” Appl. Phys. Lett. 106(13), 131104 (2015).

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(1), 011102 (2017).
[PubMed]

Y. Chen, H. Wu, E. Han, G. Yue, Z. Chen, Z. Wu, G. Wang, and H. Jiang, “High hole concentration in p-type AlGaN by indium-surfactant-assisted Mg-delta doping,” Appl. Phys. Lett. 106(16), 162102 (2015).

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).

IEEE Photonics Technol. Lett. (1)

M. Martens, F. Mehnke, C. Kuhn, C. Reich, V. Kueller, A. Knauer, C. Netzel, C. Hartmann, J. Wollweber, J. Rass, T. Wernicke, M. Bickermann, M. Weyers, and M. Kneissl, “Performance characteristics of UV-C AlGaN-based lasers grown on sapphire and bulk AlN substrates,” IEEE Photonics Technol. Lett. 26(4), 342–345 (2014).

J. Appl. Phys. (2)

C. P. Wang and Y. R. Wu, “Study of optical anisotropy in nonpolar and semipolar AlGaN quantum well deep ultraviolet light emission diode,” J. Appl. Phys. 112(3), 033104 (2012).

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

J. Cryst. Growth (1)

M. Imura, K. Nakano, G. Narita, N. Fujimoto, N. Okada, K. Balakrishnan, M. Iwaya, S. Kamiyama, H. Amano, I. Akasaki, T. Noro, T. Takagi, and A. Bandoh, “Epitaxial lateral overgrowth of AlN on trench-patterned AlN layers,” J. Cryst. Growth 298, 257–260 (2007).

J. Phys. D Appl. Phys. (1)

O. Ambacher, “Growth and applications of group III-nitrides,” J. Phys. D Appl. Phys. 31(20), 2653–2710 (1998).

Jpn. J. Appl. Phys. (1)

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(10), 100209 (2014).

Nanotechnology (1)

T. F. Kent, S. D. Carnevale, A. T. M. Sarwar, P. J. Phillips, R. F. Klie, and R. C. Myers, “Deep ultraviolet emitting polarization induced nanowire light emitting diodes with AlxGa1-xN active regions,” Nanotechnology 25(45), 455201 (2014).
[PubMed]

Opt. Express (4)

Opt. Lett. (1)

Phys. Rev. B (2)

C. Stampfl and C. G. Van de Walle, “Density-functional calculations for III-V nitrides using the local-density approximation and the generalized gradient approximation,” Phys. Rev. B 59(8), 5521–5535 (1999).

S. L. Chuang and C. S. Chang, “k·p method for strained wurtzite semiconductors,” Phys. Rev. B 54(4), 2491–2504 (1996).

Phys. Status Solidi (1)

Y. T. Moon, Y. Fu, F. Yun, S. Dogan, M. Mikkelson, D. Johnstone, and H. Morkoç, “A study of GaN regrowth on the micro-facetted GaN template formed by in-situ thermal etching,” Phys. Status Solidi 202(5), 718–721 (2005).

Phys. Status Solidi., C Curr. Top. Solid State Phys. (1)

H. Hirayama, S. Fujikawa, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “Fabrication of a low threading dislocation density ELO-AlN template for application to deep-UV LEDs,” Phys. Status Solidi., C Curr. Top. Solid State Phys. 6(S2), S356–S359 (2009).

Semicond. Sci. Technol. (2)

M. Kneissl, T. Kolbe, C. Chua, V. Kueller, N. Lobo, J. Stellmach, A. Knauer, H. Rodriguez, S. Einfeldt, and Z. Yang, “Advances in group III-nitride-based deep UV light-emitting diode technology,” Semicond. Sci. Technol. 26(1), 014036 (2011).

S. L. Chuang and C. S. Chang, “A band-structure model of strained quantum-well wurtzite semiconductors,” Semicond. Sci. Technol. 12(3), 252–263 (1997).

Other (1)

The simulation program can be downloaded at http://yrwu-wk.ee.ntu.edu.tw/ .

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Figures (8)

Fig. 1
Fig. 1 Temporal variations of growth temperature, NH3, TMAl/TEGa, TMAl/TMGa, and H2 flow rates during the growth of a QW period.
Fig. 2
Fig. 2 (a)-(c): High-resolution bright-field TEM images of samples A-C, respectively, around the QWs. (d): HAADF image of sample A with the Al content distribution in the three-period QW structure being schematically demonstrated by the line-segment drawing on the right.
Fig. 3
Fig. 3 (a): A TEM image of sample C around the QW portion. (b): GPA image corresponding to the TEM image in part (a). (c): Strain distribution along the pink dashed line in part (b).
Fig. 4
Fig. 4 (a)-(c): RSM images on the (105) plane of samples A-C, respectively.
Fig. 5
Fig. 5 XRD ω-2θ scan profile (Exp.) and its best fitting curve (Fit.) of sample A. The insert schematically shows the multi-stage-QB QW structure used for XRD fitting.
Fig. 6
Fig. 6 (a): Setup used for measuring the polarization-resolved edge-emission PL spectra. (b)-(d): PL spectra of the TE and TM polarizations of samples A-C, respectively.
Fig. 7
Fig. 7 (a): Setup used for measuring the polarization-resolved edge-emission PL spectra under a pressure along the c-axis of a sample, which is produced by a one-axis translation stage. (b)-(d): PL spectral peak wavelengths of the TE- and TM-polarized emissions under different stresses of samples A-C, respectively.
Fig. 8
Fig. 8 Schematic demonstrations of the atomic structure in the process for forming an HAL. (a): Before hydrogen back-etching. (b): After hydrogen back-etching. (c): After hydrogen back-etching and nitridation. (d): After the resupplies of Al and Ga sources.

Tables (4)

Tables Icon

Table 1 Coordinates of the central points (maximum intensities) of the AlN-buffer and AlGaN-template features, Qx and Qz, in Fig. 4 and the corresponding lattice constants, a and c, of the three samples.

Tables Icon

Table 2 Thicknesses and Al contents of various layers in the three samples obtained from XRD fitting.

Tables Icon

Table 3 PL spectral peak wavelengths and simulated emission wavelengths of the TE- and TM-polarized emissions (λTE and λTM, respectively) and their differences of the three samples.

Tables Icon

Table 4 PL spectral peak wavelengths of the TE- and TM-polarized emissions (λTE and λTM, respectively) and their differences of the three samples under zero and 10.6 kPa stresses.

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