Abstract

We report the successful fabrication of a compact deep ultraviolet emission device via a marriage of AlGaN quantum wells and graphene nanoneedle field electron emitters. The device demonstrated a 20-mW deep ultraviolet output power and an approximately 4% power efficiency. The performance of this device may lead toward the realization of an environmentally friendly, convenient and practical deep ultraviolet light source.

© 2012 OSA

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  4. K. Watanabe, T. Taniguchi, T. Niiyama, K. Miya, and M. Taniguchi, “Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride,” Nat. Photonics3(10), 591–594 (2009).
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    [CrossRef]
  28. D. Brunner, H. Angerer, E. Bustarret, F. Freudenberg, R. Höpler, R. Dimitrov, O. Ambacher, and M. Stutzmann, “Optical constants of epitaxial AlGaN films and their temperature dependence,” J. Appl. Phys.82(10), 5090–5096 (1997).
    [CrossRef]
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2011

Y. Shimahara, H. Miyake, K. Hiramatsu, F. Fukuyo, T. Okada, H. Takaoka, and H. Yoshida, “Fabrication of deep-ultraviolet-light-source tube using Si-doped AlGaN,” Appl. Phys. Express4(4), 042103 (2011).
[CrossRef]

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 multi quantum-barrier electron blocking layer,” Appl. Phys. Express3(3), 031002 (2010).
[CrossRef]

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

T. Oto, R. G. Banal, K. Kataoka, M. Funato, and Y. Kawakami, “100 mW deep-ultraviolet emission from aluminium-nitride-based quantum wells pumped by an electron beam,” Nat. Photonics4(11), 767–770 (2010).
[CrossRef]

2009

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 A206(6), 1176–1182 (2009).
[CrossRef]

A. Bhattacharyya, T. D. Moustakas, L. Zhou, D. J. Smith, and W. Hug, “Deep ultraviolet emitting AlGaN quantum wells with high internal quantum efficiency,” Appl. Phys. Lett.94(18), 181907 (2009).
[CrossRef]

H. Watanabe, C. E. Nebel, and S. Shikata, “Isotopic homojunction band engineering from diamond,” Science324(5933), 1425–1428 (2009).
[CrossRef] [PubMed]

K. Watanabe, T. Taniguchi, T. Niiyama, K. Miya, and M. Taniguchi, “Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride,” Nat. Photonics3(10), 591–594 (2009).
[CrossRef]

2008

A. Khan, K. Balakrishnan, and T. Katona, “Ultraviolet light-emitting diodes based on group three nitrides,” Nat. Photonics2(2), 77–84 (2008).
[CrossRef]

T. Matsumoto, Y. Neo, H. Mimura, and M. Tomita, “Determining the physisorption energies of molecules on graphene nanostructures by measuring the stochastic emission-current fluctuation,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys.77(3), 031611 (2008).
[CrossRef] [PubMed]

2007

T. Matsumoto, Y. Neo, H. Mimura, M. Tomita, and N. Minami, “Stabilization of electron emission from nanoneedles with two dimensional graphene sheet structure in a high residual pressure region,” Appl. Phys. Lett.90(10), 103516 (2007).
[CrossRef]

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

Y. Kubota, K. Watanabe, O. Tsuda, and T. Taniguchi, “Deep ultraviolet light-emitting hexagonal boron nitride synthesized at atmospheric pressure,” Science317(5840), 932–934 (2007).
[CrossRef] [PubMed]

A. K. Geim and K. S. Novoselov, “The rise of graphene,” Nat. Mater.6(3), 183–191 (2007).
[CrossRef] [PubMed]

D. Drouin, A. R. Couture, D. Joly, X. Tastet, V. Aimez, and R. Gauvin, “CASINO V2.42: a fast and easy-to-use modeling tool for scanning electron microscopy and microanalysis users,” Scanning29(3), 92–101 (2007).
[CrossRef] [PubMed]

2006

Y. Taniyasu, M. Kasu, and T. Makimoto, “An aluminium nitride light-emitting diode with a wavelength of 210 nanometres,” Nature441(7091), 325–328 (2006).
[CrossRef] [PubMed]

2005

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, “Two-dimensional gas of massless Dirac fermions in graphene,” Nature438(7065), 197–200 (2005).
[CrossRef] [PubMed]

Y. Zhang, Y. W. Tan, H. L. Stormer, and P. Kim, “Experimental observation of the quantum Hall effect and Berry’s phase in graphene,” Nature438(7065), 201–204 (2005).
[CrossRef] [PubMed]

J. Zhang, X. Hu, A. Lunev, J. Deng, Y. Bilenko, T. M. Katona, M. S. Shur, R. Gaska, and A. Khan, “AlGaN deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys.44(10), 7250–7253 (2005).
[CrossRef]

2004

K. Watanabe, T. Taniguchi, and H. Kanda, “Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal,” Nat. Mater.3(6), 404–409 (2004).
[CrossRef] [PubMed]

2003

J. Li, B. Nam, M. L. Nakarmi, J. Y. Lin, H. X. Jiang, P. Carrier, and S.-H. Wei, “Band structure and fundamental optical transitions in wurtzite AlN,” Appl. Phys. Lett.83(25), 5163–5165 (2003).
[CrossRef]

1998

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

1997

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

D. Brunner, H. Angerer, E. Bustarret, F. Freudenberg, R. Höpler, R. Dimitrov, O. Ambacher, and M. Stutzmann, “Optical constants of epitaxial AlGaN films and their temperature dependence,” J. Appl. Phys.82(10), 5090–5096 (1997).
[CrossRef]

1986

H. Amano, N. Sawaki, I. Akasaki, and Y. Toyoda, “Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer,” Appl. Phys. Lett.48(5), 353–355 (1986).
[CrossRef]

1963

S. G. Tomlin, “The back scattering of electrons from solids,” Proc. Phys. Soc. Lond.82(3), 465–466 (1963).
[CrossRef]

1952

W. Shockley and T. Read, “Statistics of the recombination of holes and electrons,” Phys. Rev.87(5), 835–842 (1952).
[CrossRef]

1930

H. A. Bethe, “On the theory of the passage of fast particles through matter,” Ann. Phys.5, 325–400 (1930).
[CrossRef]

Aimez, V.

D. Drouin, A. R. Couture, D. Joly, X. Tastet, V. Aimez, and R. Gauvin, “CASINO V2.42: a fast and easy-to-use modeling tool for scanning electron microscopy and microanalysis users,” Scanning29(3), 92–101 (2007).
[CrossRef] [PubMed]

Akasaki, I.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

H. Amano, N. Sawaki, I. Akasaki, and Y. Toyoda, “Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer,” Appl. Phys. Lett.48(5), 353–355 (1986).
[CrossRef]

Albrecht, M.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

Amano, H.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

H. Amano, N. Sawaki, I. Akasaki, and Y. Toyoda, “Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer,” Appl. Phys. Lett.48(5), 353–355 (1986).
[CrossRef]

Ambacher, O.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

D. Brunner, H. Angerer, E. Bustarret, F. Freudenberg, R. Höpler, R. Dimitrov, O. Ambacher, and M. Stutzmann, “Optical constants of epitaxial AlGaN films and their temperature dependence,” J. Appl. Phys.82(10), 5090–5096 (1997).
[CrossRef]

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

Angerer, H.

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

D. Brunner, H. Angerer, E. Bustarret, F. Freudenberg, R. Höpler, R. Dimitrov, O. Ambacher, and M. Stutzmann, “Optical constants of epitaxial AlGaN films and their temperature dependence,” J. Appl. Phys.82(10), 5090–5096 (1997).
[CrossRef]

Balakrishnan, K.

A. Khan, K. Balakrishnan, and T. Katona, “Ultraviolet light-emitting diodes based on group three nitrides,” Nat. Photonics2(2), 77–84 (2008).
[CrossRef]

Banal, R. G.

T. Oto, R. G. Banal, K. Kataoka, M. Funato, and Y. Kawakami, “100 mW deep-ultraviolet emission from aluminium-nitride-based quantum wells pumped by an electron beam,” Nat. Photonics4(11), 767–770 (2010).
[CrossRef]

Bergmaier, A.

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

Bethe, H. A.

H. A. Bethe, “On the theory of the passage of fast particles through matter,” Ann. Phys.5, 325–400 (1930).
[CrossRef]

Bhattacharyya, A.

A. Bhattacharyya, T. D. Moustakas, L. Zhou, D. J. Smith, and W. Hug, “Deep ultraviolet emitting AlGaN quantum wells with high internal quantum efficiency,” Appl. Phys. Lett.94(18), 181907 (2009).
[CrossRef]

Bilenko, Y.

J. Zhang, X. Hu, A. Lunev, J. Deng, Y. Bilenko, T. M. Katona, M. S. Shur, R. Gaska, and A. Khan, “AlGaN deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys.44(10), 7250–7253 (2005).
[CrossRef]

Born, E.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

Brunner, D.

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

D. Brunner, H. Angerer, E. Bustarret, F. Freudenberg, R. Höpler, R. Dimitrov, O. Ambacher, and M. Stutzmann, “Optical constants of epitaxial AlGaN films and their temperature dependence,” J. Appl. Phys.82(10), 5090–5096 (1997).
[CrossRef]

Bustarret, E.

D. Brunner, H. Angerer, E. Bustarret, F. Freudenberg, R. Höpler, R. Dimitrov, O. Ambacher, and M. Stutzmann, “Optical constants of epitaxial AlGaN films and their temperature dependence,” J. Appl. Phys.82(10), 5090–5096 (1997).
[CrossRef]

Carrier, P.

J. Li, B. Nam, M. L. Nakarmi, J. Y. Lin, H. X. Jiang, P. Carrier, and S.-H. Wei, “Band structure and fundamental optical transitions in wurtzite AlN,” Appl. Phys. Lett.83(25), 5163–5165 (2003).
[CrossRef]

Christiansen, S.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

Couture, A. R.

D. Drouin, A. R. Couture, D. Joly, X. Tastet, V. Aimez, and R. Gauvin, “CASINO V2.42: a fast and easy-to-use modeling tool for scanning electron microscopy and microanalysis users,” Scanning29(3), 92–101 (2007).
[CrossRef] [PubMed]

Deng, J.

J. Zhang, X. Hu, A. Lunev, J. Deng, Y. Bilenko, T. M. Katona, M. S. Shur, R. Gaska, and A. Khan, “AlGaN deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys.44(10), 7250–7253 (2005).
[CrossRef]

Dimitrov, R.

D. Brunner, H. Angerer, E. Bustarret, F. Freudenberg, R. Höpler, R. Dimitrov, O. Ambacher, and M. Stutzmann, “Optical constants of epitaxial AlGaN films and their temperature dependence,” J. Appl. Phys.82(10), 5090–5096 (1997).
[CrossRef]

Dollinger, G.

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

Drouin, D.

D. Drouin, A. R. Couture, D. Joly, X. Tastet, V. Aimez, and R. Gauvin, “CASINO V2.42: a fast and easy-to-use modeling tool for scanning electron microscopy and microanalysis users,” Scanning29(3), 92–101 (2007).
[CrossRef] [PubMed]

Dubonos, S. V.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, “Two-dimensional gas of massless Dirac fermions in graphene,” Nature438(7065), 197–200 (2005).
[CrossRef] [PubMed]

Firsov, A. A.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, “Two-dimensional gas of massless Dirac fermions in graphene,” Nature438(7065), 197–200 (2005).
[CrossRef] [PubMed]

Freudenberg, F.

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

D. Brunner, H. Angerer, E. Bustarret, F. Freudenberg, R. Höpler, R. Dimitrov, O. Ambacher, and M. Stutzmann, “Optical constants of epitaxial AlGaN films and their temperature dependence,” J. Appl. Phys.82(10), 5090–5096 (1997).
[CrossRef]

Fujikawa, S.

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A206(6), 1176–1182 (2009).
[CrossRef]

Fujita, T.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

Fukahori, S.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

Fukuyo, F.

Y. Shimahara, H. Miyake, K. Hiramatsu, F. Fukuyo, T. Okada, H. Takaoka, and H. Yoshida, “Fabrication of deep-ultraviolet-light-source tube using Si-doped AlGaN,” Appl. Phys. Express4(4), 042103 (2011).
[CrossRef]

Funato, M.

T. Oto, R. G. Banal, K. Kataoka, M. Funato, and Y. Kawakami, “100 mW deep-ultraviolet emission from aluminium-nitride-based quantum wells pumped by an electron beam,” Nat. Photonics4(11), 767–770 (2010).
[CrossRef]

Gaska, R.

J. Zhang, X. Hu, A. Lunev, J. Deng, Y. Bilenko, T. M. Katona, M. S. Shur, R. Gaska, and A. Khan, “AlGaN deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys.44(10), 7250–7253 (2005).
[CrossRef]

Gauvin, R.

D. Drouin, A. R. Couture, D. Joly, X. Tastet, V. Aimez, and R. Gauvin, “CASINO V2.42: a fast and easy-to-use modeling tool for scanning electron microscopy and microanalysis users,” Scanning29(3), 92–101 (2007).
[CrossRef] [PubMed]

Geim, A. K.

A. K. Geim and K. S. Novoselov, “The rise of graphene,” Nat. Mater.6(3), 183–191 (2007).
[CrossRef] [PubMed]

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, “Two-dimensional gas of massless Dirac fermions in graphene,” Nature438(7065), 197–200 (2005).
[CrossRef] [PubMed]

Göbeli, H.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

Grigorieva, I. V.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, “Two-dimensional gas of massless Dirac fermions in graphene,” Nature438(7065), 197–200 (2005).
[CrossRef] [PubMed]

Hiramatsu, K.

Y. Shimahara, H. Miyake, K. Hiramatsu, F. Fukuyo, T. Okada, H. Takaoka, and H. Yoshida, “Fabrication of deep-ultraviolet-light-source tube using Si-doped AlGaN,” Appl. Phys. Express4(4), 042103 (2011).
[CrossRef]

Hirano, A.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

Hirayama, H.

H. Hirayama, Y. Tsukada, T. Maeda, and N. Kamata, “Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multi quantum-barrier electron blocking layer,” Appl. Phys. Express3(3), 031002 (2010).
[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 A206(6), 1176–1182 (2009).
[CrossRef]

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

Höpler, R.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

D. Brunner, H. Angerer, E. Bustarret, F. Freudenberg, R. Höpler, R. Dimitrov, O. Ambacher, and M. Stutzmann, “Optical constants of epitaxial AlGaN films and their temperature dependence,” J. Appl. Phys.82(10), 5090–5096 (1997).
[CrossRef]

Hu, X.

J. Zhang, X. Hu, A. Lunev, J. Deng, Y. Bilenko, T. M. Katona, M. S. Shur, R. Gaska, and A. Khan, “AlGaN deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys.44(10), 7250–7253 (2005).
[CrossRef]

Hug, W.

A. Bhattacharyya, T. D. Moustakas, L. Zhou, D. J. Smith, and W. Hug, “Deep ultraviolet emitting AlGaN quantum wells with high internal quantum efficiency,” Appl. Phys. Lett.94(18), 181907 (2009).
[CrossRef]

Inazu, T.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

Ippommatsu, M.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

Iwaya, M.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

Jiang, D.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, “Two-dimensional gas of massless Dirac fermions in graphene,” Nature438(7065), 197–200 (2005).
[CrossRef] [PubMed]

Jiang, H. X.

J. Li, B. Nam, M. L. Nakarmi, J. Y. Lin, H. X. Jiang, P. Carrier, and S.-H. Wei, “Band structure and fundamental optical transitions in wurtzite AlN,” Appl. Phys. Lett.83(25), 5163–5165 (2003).
[CrossRef]

Joly, D.

D. Drouin, A. R. Couture, D. Joly, X. Tastet, V. Aimez, and R. Gauvin, “CASINO V2.42: a fast and easy-to-use modeling tool for scanning electron microscopy and microanalysis users,” Scanning29(3), 92–101 (2007).
[CrossRef] [PubMed]

Kamata, N.

H. Hirayama, Y. Tsukada, T. Maeda, and N. Kamata, “Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multi quantum-barrier electron blocking layer,” Appl. Phys. Express3(3), 031002 (2010).
[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 A206(6), 1176–1182 (2009).
[CrossRef]

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

Kamiyama, S.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

Kanda, H.

K. Watanabe, T. Taniguchi, and H. Kanda, “Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal,” Nat. Mater.3(6), 404–409 (2004).
[CrossRef] [PubMed]

Karsch, S.

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

Kasu, M.

Y. Taniyasu, M. Kasu, and T. Makimoto, “An aluminium nitride light-emitting diode with a wavelength of 210 nanometres,” Nature441(7091), 325–328 (2006).
[CrossRef] [PubMed]

Kataoka, K.

T. Oto, R. G. Banal, K. Kataoka, M. Funato, and Y. Kawakami, “100 mW deep-ultraviolet emission from aluminium-nitride-based quantum wells pumped by an electron beam,” Nat. Photonics4(11), 767–770 (2010).
[CrossRef]

Katona, T.

A. Khan, K. Balakrishnan, and T. Katona, “Ultraviolet light-emitting diodes based on group three nitrides,” Nat. Photonics2(2), 77–84 (2008).
[CrossRef]

Katona, T. M.

J. Zhang, X. Hu, A. Lunev, J. Deng, Y. Bilenko, T. M. Katona, M. S. Shur, R. Gaska, and A. Khan, “AlGaN deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys.44(10), 7250–7253 (2005).
[CrossRef]

Katsnelson, M. I.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, “Two-dimensional gas of massless Dirac fermions in graphene,” Nature438(7065), 197–200 (2005).
[CrossRef] [PubMed]

Kawakami, Y.

T. Oto, R. G. Banal, K. Kataoka, M. Funato, and Y. Kawakami, “100 mW deep-ultraviolet emission from aluminium-nitride-based quantum wells pumped by an electron beam,” Nat. Photonics4(11), 767–770 (2010).
[CrossRef]

Khan, A.

A. Khan, K. Balakrishnan, and T. Katona, “Ultraviolet light-emitting diodes based on group three nitrides,” Nat. Photonics2(2), 77–84 (2008).
[CrossRef]

J. Zhang, X. Hu, A. Lunev, J. Deng, Y. Bilenko, T. M. Katona, M. S. Shur, R. Gaska, and A. Khan, “AlGaN deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys.44(10), 7250–7253 (2005).
[CrossRef]

Kim, M.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

Kim, P.

Y. Zhang, Y. W. Tan, H. L. Stormer, and P. Kim, “Experimental observation of the quantum Hall effect and Berry’s phase in graphene,” Nature438(7065), 201–204 (2005).
[CrossRef] [PubMed]

Körner, H.-J.

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

Kubota, Y.

Y. Kubota, K. Watanabe, O. Tsuda, and T. Taniguchi, “Deep ultraviolet light-emitting hexagonal boron nitride synthesized at atmospheric pressure,” Science317(5840), 932–934 (2007).
[CrossRef] [PubMed]

Li, J.

J. Li, B. Nam, M. L. Nakarmi, J. Y. Lin, H. X. Jiang, P. Carrier, and S.-H. Wei, “Band structure and fundamental optical transitions in wurtzite AlN,” Appl. Phys. Lett.83(25), 5163–5165 (2003).
[CrossRef]

Lin, J. Y.

J. Li, B. Nam, M. L. Nakarmi, J. Y. Lin, H. X. Jiang, P. Carrier, and S.-H. Wei, “Band structure and fundamental optical transitions in wurtzite AlN,” Appl. Phys. Lett.83(25), 5163–5165 (2003).
[CrossRef]

Lunev, A.

J. Zhang, X. Hu, A. Lunev, J. Deng, Y. Bilenko, T. M. Katona, M. S. Shur, R. Gaska, and A. Khan, “AlGaN deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys.44(10), 7250–7253 (2005).
[CrossRef]

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 multi quantum-barrier electron blocking layer,” Appl. Phys. Express3(3), 031002 (2010).
[CrossRef]

Makimoto, T.

Y. Taniyasu, M. Kasu, and T. Makimoto, “An aluminium nitride light-emitting diode with a wavelength of 210 nanometres,” Nature441(7091), 325–328 (2006).
[CrossRef] [PubMed]

Matsumoto, T.

T. Matsumoto, Y. Neo, H. Mimura, and M. Tomita, “Determining the physisorption energies of molecules on graphene nanostructures by measuring the stochastic emission-current fluctuation,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys.77(3), 031611 (2008).
[CrossRef] [PubMed]

T. Matsumoto, Y. Neo, H. Mimura, M. Tomita, and N. Minami, “Stabilization of electron emission from nanoneedles with two dimensional graphene sheet structure in a high residual pressure region,” Appl. Phys. Lett.90(10), 103516 (2007).
[CrossRef]

Metzger, T.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

Mimura, H.

T. Matsumoto, Y. Neo, H. Mimura, and M. Tomita, “Determining the physisorption energies of molecules on graphene nanostructures by measuring the stochastic emission-current fluctuation,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys.77(3), 031611 (2008).
[CrossRef] [PubMed]

T. Matsumoto, Y. Neo, H. Mimura, M. Tomita, and N. Minami, “Stabilization of electron emission from nanoneedles with two dimensional graphene sheet structure in a high residual pressure region,” Appl. Phys. Lett.90(10), 103516 (2007).
[CrossRef]

Minami, N.

T. Matsumoto, Y. Neo, H. Mimura, M. Tomita, and N. Minami, “Stabilization of electron emission from nanoneedles with two dimensional graphene sheet structure in a high residual pressure region,” Appl. Phys. Lett.90(10), 103516 (2007).
[CrossRef]

Miya, K.

K. Watanabe, T. Taniguchi, T. Niiyama, K. Miya, and M. Taniguchi, “Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride,” Nat. Photonics3(10), 591–594 (2009).
[CrossRef]

Miyake, H.

Y. Shimahara, H. Miyake, K. Hiramatsu, F. Fukuyo, T. Okada, H. Takaoka, and H. Yoshida, “Fabrication of deep-ultraviolet-light-source tube using Si-doped AlGaN,” Appl. Phys. Express4(4), 042103 (2011).
[CrossRef]

Morozov, S. V.

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, “Two-dimensional gas of massless Dirac fermions in graphene,” Nature438(7065), 197–200 (2005).
[CrossRef] [PubMed]

Moustakas, T. D.

A. Bhattacharyya, T. D. Moustakas, L. Zhou, D. J. Smith, and W. Hug, “Deep ultraviolet emitting AlGaN quantum wells with high internal quantum efficiency,” Appl. Phys. Lett.94(18), 181907 (2009).
[CrossRef]

Nagasawa, Y.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

Nakarmi, M. L.

J. Li, B. Nam, M. L. Nakarmi, J. Y. Lin, H. X. Jiang, P. Carrier, and S.-H. Wei, “Band structure and fundamental optical transitions in wurtzite AlN,” Appl. Phys. Lett.83(25), 5163–5165 (2003).
[CrossRef]

Nam, B.

J. Li, B. Nam, M. L. Nakarmi, J. Y. Lin, H. X. Jiang, P. Carrier, and S.-H. Wei, “Band structure and fundamental optical transitions in wurtzite AlN,” Appl. Phys. Lett.83(25), 5163–5165 (2003).
[CrossRef]

Nebel, C. E.

H. Watanabe, C. E. Nebel, and S. Shikata, “Isotopic homojunction band engineering from diamond,” Science324(5933), 1425–1428 (2009).
[CrossRef] [PubMed]

Neo, Y.

T. Matsumoto, Y. Neo, H. Mimura, and M. Tomita, “Determining the physisorption energies of molecules on graphene nanostructures by measuring the stochastic emission-current fluctuation,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys.77(3), 031611 (2008).
[CrossRef] [PubMed]

T. Matsumoto, Y. Neo, H. Mimura, M. Tomita, and N. Minami, “Stabilization of electron emission from nanoneedles with two dimensional graphene sheet structure in a high residual pressure region,” Appl. Phys. Lett.90(10), 103516 (2007).
[CrossRef]

Niiyama, T.

K. Watanabe, T. Taniguchi, T. Niiyama, K. Miya, and M. Taniguchi, “Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride,” Nat. Photonics3(10), 591–594 (2009).
[CrossRef]

Noguchi, N.

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A206(6), 1176–1182 (2009).
[CrossRef]

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

Norimatsu, J.

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A206(6), 1176–1182 (2009).
[CrossRef]

Novoselov, K. S.

A. K. Geim and K. S. Novoselov, “The rise of graphene,” Nat. Mater.6(3), 183–191 (2007).
[CrossRef] [PubMed]

K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson, I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, “Two-dimensional gas of massless Dirac fermions in graphene,” Nature438(7065), 197–200 (2005).
[CrossRef] [PubMed]

Ohashi, T.

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

Okada, T.

Y. Shimahara, H. Miyake, K. Hiramatsu, F. Fukuyo, T. Okada, H. Takaoka, and H. Yoshida, “Fabrication of deep-ultraviolet-light-source tube using Si-doped AlGaN,” Appl. Phys. Express4(4), 042103 (2011).
[CrossRef]

Oto, T.

T. Oto, R. G. Banal, K. Kataoka, M. Funato, and Y. Kawakami, “100 mW deep-ultraviolet emission from aluminium-nitride-based quantum wells pumped by an electron beam,” Nat. Photonics4(11), 767–770 (2010).
[CrossRef]

Pernot, C.

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

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W. Shockley and T. Read, “Statistics of the recombination of holes and electrons,” Phys. Rev.87(5), 835–842 (1952).
[CrossRef]

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H. Amano, N. Sawaki, I. Akasaki, and Y. Toyoda, “Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer,” Appl. Phys. Lett.48(5), 353–355 (1986).
[CrossRef]

Schuster, M.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

Shikata, S.

H. Watanabe, C. E. Nebel, and S. Shikata, “Isotopic homojunction band engineering from diamond,” Science324(5933), 1425–1428 (2009).
[CrossRef] [PubMed]

Shimahara, Y.

Y. Shimahara, H. Miyake, K. Hiramatsu, F. Fukuyo, T. Okada, H. Takaoka, and H. Yoshida, “Fabrication of deep-ultraviolet-light-source tube using Si-doped AlGaN,” Appl. Phys. Express4(4), 042103 (2011).
[CrossRef]

Shockley, W.

W. Shockley and T. Read, “Statistics of the recombination of holes and electrons,” Phys. Rev.87(5), 835–842 (1952).
[CrossRef]

Shur, M. S.

J. Zhang, X. Hu, A. Lunev, J. Deng, Y. Bilenko, T. M. Katona, M. S. Shur, R. Gaska, and A. Khan, “AlGaN deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys.44(10), 7250–7253 (2005).
[CrossRef]

Smith, D. J.

A. Bhattacharyya, T. D. Moustakas, L. Zhou, D. J. Smith, and W. Hug, “Deep ultraviolet emitting AlGaN quantum wells with high internal quantum efficiency,” Appl. Phys. Lett.94(18), 181907 (2009).
[CrossRef]

Stömmer, R.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

Stormer, H. L.

Y. Zhang, Y. W. Tan, H. L. Stormer, and P. Kim, “Experimental observation of the quantum Hall effect and Berry’s phase in graphene,” Nature438(7065), 201–204 (2005).
[CrossRef] [PubMed]

Strunk, H. P.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

Stutzmann, M.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
[CrossRef]

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

D. Brunner, H. Angerer, E. Bustarret, F. Freudenberg, R. Höpler, R. Dimitrov, O. Ambacher, and M. Stutzmann, “Optical constants of epitaxial AlGaN films and their temperature dependence,” J. Appl. Phys.82(10), 5090–5096 (1997).
[CrossRef]

Takano, T.

H. Hirayama, S. Fujikawa, N. Noguchi, J. Norimatsu, T. Takano, K. Tsubaki, and N. Kamata, “222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire,” Phys. Status Solidi A206(6), 1176–1182 (2009).
[CrossRef]

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Y. Shimahara, H. Miyake, K. Hiramatsu, F. Fukuyo, T. Okada, H. Takaoka, and H. Yoshida, “Fabrication of deep-ultraviolet-light-source tube using Si-doped AlGaN,” Appl. Phys. Express4(4), 042103 (2011).
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Y. Zhang, Y. W. Tan, H. L. Stormer, and P. Kim, “Experimental observation of the quantum Hall effect and Berry’s phase in graphene,” Nature438(7065), 201–204 (2005).
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Taniguchi, M.

K. Watanabe, T. Taniguchi, T. Niiyama, K. Miya, and M. Taniguchi, “Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride,” Nat. Photonics3(10), 591–594 (2009).
[CrossRef]

Taniguchi, T.

K. Watanabe, T. Taniguchi, T. Niiyama, K. Miya, and M. Taniguchi, “Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride,” Nat. Photonics3(10), 591–594 (2009).
[CrossRef]

Y. Kubota, K. Watanabe, O. Tsuda, and T. Taniguchi, “Deep ultraviolet light-emitting hexagonal boron nitride synthesized at atmospheric pressure,” Science317(5840), 932–934 (2007).
[CrossRef] [PubMed]

K. Watanabe, T. Taniguchi, and H. Kanda, “Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal,” Nat. Mater.3(6), 404–409 (2004).
[CrossRef] [PubMed]

Taniyasu, Y.

Y. Taniyasu, M. Kasu, and T. Makimoto, “An aluminium nitride light-emitting diode with a wavelength of 210 nanometres,” Nature441(7091), 325–328 (2006).
[CrossRef] [PubMed]

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D. Drouin, A. R. Couture, D. Joly, X. Tastet, V. Aimez, and R. Gauvin, “CASINO V2.42: a fast and easy-to-use modeling tool for scanning electron microscopy and microanalysis users,” Scanning29(3), 92–101 (2007).
[CrossRef] [PubMed]

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T. Matsumoto, Y. Neo, H. Mimura, and M. Tomita, “Determining the physisorption energies of molecules on graphene nanostructures by measuring the stochastic emission-current fluctuation,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys.77(3), 031611 (2008).
[CrossRef] [PubMed]

T. Matsumoto, Y. Neo, H. Mimura, M. Tomita, and N. Minami, “Stabilization of electron emission from nanoneedles with two dimensional graphene sheet structure in a high residual pressure region,” Appl. Phys. Lett.90(10), 103516 (2007).
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[CrossRef]

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H. Amano, N. Sawaki, I. Akasaki, and Y. Toyoda, “Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer,” Appl. Phys. Lett.48(5), 353–355 (1986).
[CrossRef]

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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 A206(6), 1176–1182 (2009).
[CrossRef]

Tsuda, O.

Y. Kubota, K. Watanabe, O. Tsuda, and T. Taniguchi, “Deep ultraviolet light-emitting hexagonal boron nitride synthesized at atmospheric pressure,” Science317(5840), 932–934 (2007).
[CrossRef] [PubMed]

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H. Hirayama, Y. Tsukada, T. Maeda, and N. Kamata, “Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multi quantum-barrier electron blocking layer,” Appl. Phys. Express3(3), 031002 (2010).
[CrossRef]

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H. Watanabe, C. E. Nebel, and S. Shikata, “Isotopic homojunction band engineering from diamond,” Science324(5933), 1425–1428 (2009).
[CrossRef] [PubMed]

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K. Watanabe, T. Taniguchi, T. Niiyama, K. Miya, and M. Taniguchi, “Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride,” Nat. Photonics3(10), 591–594 (2009).
[CrossRef]

Y. Kubota, K. Watanabe, O. Tsuda, and T. Taniguchi, “Deep ultraviolet light-emitting hexagonal boron nitride synthesized at atmospheric pressure,” Science317(5840), 932–934 (2007).
[CrossRef] [PubMed]

K. Watanabe, T. Taniguchi, and H. Kanda, “Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal,” Nat. Mater.3(6), 404–409 (2004).
[CrossRef] [PubMed]

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J. Li, B. Nam, M. L. Nakarmi, J. Y. Lin, H. X. Jiang, P. Carrier, and S.-H. Wei, “Band structure and fundamental optical transitions in wurtzite AlN,” Appl. Phys. Lett.83(25), 5163–5165 (2003).
[CrossRef]

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

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Y. Shimahara, H. Miyake, K. Hiramatsu, F. Fukuyo, T. Okada, H. Takaoka, and H. Yoshida, “Fabrication of deep-ultraviolet-light-source tube using Si-doped AlGaN,” Appl. Phys. Express4(4), 042103 (2011).
[CrossRef]

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J. Zhang, X. Hu, A. Lunev, J. Deng, Y. Bilenko, T. M. Katona, M. S. Shur, R. Gaska, and A. Khan, “AlGaN deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys.44(10), 7250–7253 (2005).
[CrossRef]

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Y. Zhang, Y. W. Tan, H. L. Stormer, and P. Kim, “Experimental observation of the quantum Hall effect and Berry’s phase in graphene,” Nature438(7065), 201–204 (2005).
[CrossRef] [PubMed]

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A. Bhattacharyya, T. D. Moustakas, L. Zhou, D. J. Smith, and W. Hug, “Deep ultraviolet emitting AlGaN quantum wells with high internal quantum efficiency,” Appl. Phys. Lett.94(18), 181907 (2009).
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H. Hirayama, Y. Tsukada, T. Maeda, and N. Kamata, “Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multi quantum-barrier electron blocking layer,” Appl. Phys. Express3(3), 031002 (2010).
[CrossRef]

C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, and H. Amano, “Improved efficiency of 255-280 nm AlGaN-based light-emitting diodes,” Appl. Phys. Express3(6), 061004 (2010).
[CrossRef]

Y. Shimahara, H. Miyake, K. Hiramatsu, F. Fukuyo, T. Okada, H. Takaoka, and H. Yoshida, “Fabrication of deep-ultraviolet-light-source tube using Si-doped AlGaN,” Appl. Phys. Express4(4), 042103 (2011).
[CrossRef]

Appl. Phys. Lett.

T. Matsumoto, Y. Neo, H. Mimura, M. Tomita, and N. Minami, “Stabilization of electron emission from nanoneedles with two dimensional graphene sheet structure in a high residual pressure region,” Appl. Phys. Lett.90(10), 103516 (2007).
[CrossRef]

A. Bhattacharyya, T. D. Moustakas, L. Zhou, D. J. Smith, and W. Hug, “Deep ultraviolet emitting AlGaN quantum wells with high internal quantum efficiency,” Appl. Phys. Lett.94(18), 181907 (2009).
[CrossRef]

H. Amano, N. Sawaki, I. Akasaki, and Y. Toyoda, “Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer,” Appl. Phys. Lett.48(5), 353–355 (1986).
[CrossRef]

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

J. Li, B. Nam, M. L. Nakarmi, J. Y. Lin, H. X. Jiang, P. Carrier, and S.-H. Wei, “Band structure and fundamental optical transitions in wurtzite AlN,” Appl. Phys. Lett.83(25), 5163–5165 (2003).
[CrossRef]

H. Angerer, D. Brunner, F. Freudenberg, O. Ambacher, M. Stutzmann, R. Höpler, T. Metzger, E. Born, G. Dollinger, A. Bergmaier, S. Karsch, and H.-J. Körner, “Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1-xN films,” Appl. Phys. Lett.71(11), 1504–1506 (1997).
[CrossRef]

J. Appl. Phys.

D. Brunner, H. Angerer, E. Bustarret, F. Freudenberg, R. Höpler, R. Dimitrov, O. Ambacher, and M. Stutzmann, “Optical constants of epitaxial AlGaN films and their temperature dependence,” J. Appl. Phys.82(10), 5090–5096 (1997).
[CrossRef]

Jpn. J. Appl. Phys.

J. Zhang, X. Hu, A. Lunev, J. Deng, Y. Bilenko, T. M. Katona, M. S. Shur, R. Gaska, and A. Khan, “AlGaN deep-ultraviolet light-emitting diodes,” Jpn. J. Appl. Phys.44(10), 7250–7253 (2005).
[CrossRef]

Nat. Mater.

K. Watanabe, T. Taniguchi, and H. Kanda, “Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal,” Nat. Mater.3(6), 404–409 (2004).
[CrossRef] [PubMed]

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Nat. Photonics

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[CrossRef]

K. Watanabe, T. Taniguchi, T. Niiyama, K. Miya, and M. Taniguchi, “Far-ultraviolet plane-emission handheld device based on hexagonal boron nitride,” Nat. Photonics3(10), 591–594 (2009).
[CrossRef]

T. Oto, R. G. Banal, K. Kataoka, M. Funato, and Y. Kawakami, “100 mW deep-ultraviolet emission from aluminium-nitride-based quantum wells pumped by an electron beam,” Nat. Photonics4(11), 767–770 (2010).
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Y. Zhang, Y. W. Tan, H. L. Stormer, and P. Kim, “Experimental observation of the quantum Hall effect and Berry’s phase in graphene,” Nature438(7065), 201–204 (2005).
[CrossRef] [PubMed]

Y. Taniyasu, M. Kasu, and T. Makimoto, “An aluminium nitride light-emitting diode with a wavelength of 210 nanometres,” Nature441(7091), 325–328 (2006).
[CrossRef] [PubMed]

Philos. Mag.

T. Metzger, R. Höpler, E. Born, O. Ambacher, M. Stutzmann, R. Stömmer, M. Schuster, H. Göbeli, S. Christiansen, M. Albrecht, and H. P. Strunk, “A-physics of condensed matter structure defects,” Philos. Mag.77, 1013–1025 (1998).
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T. Matsumoto, Y. Neo, H. Mimura, and M. Tomita, “Determining the physisorption energies of molecules on graphene nanostructures by measuring the stochastic emission-current fluctuation,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys.77(3), 031611 (2008).
[CrossRef] [PubMed]

Phys. Status Solidi A

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 A206(6), 1176–1182 (2009).
[CrossRef]

Proc. Phys. Soc. Lond.

S. G. Tomlin, “The back scattering of electrons from solids,” Proc. Phys. Soc. Lond.82(3), 465–466 (1963).
[CrossRef]

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D. Drouin, A. R. Couture, D. Joly, X. Tastet, V. Aimez, and R. Gauvin, “CASINO V2.42: a fast and easy-to-use modeling tool for scanning electron microscopy and microanalysis users,” Scanning29(3), 92–101 (2007).
[CrossRef] [PubMed]

Science

H. Watanabe, C. E. Nebel, and S. Shikata, “Isotopic homojunction band engineering from diamond,” Science324(5933), 1425–1428 (2009).
[CrossRef] [PubMed]

Y. Kubota, K. Watanabe, O. Tsuda, and T. Taniguchi, “Deep ultraviolet light-emitting hexagonal boron nitride synthesized at atmospheric pressure,” Science317(5840), 932–934 (2007).
[CrossRef] [PubMed]

Other

G. F. J. Garlick, Luminescence of Inorganic Solids (Academic Press, New York, 1966), Chap. 12.

T. Matsumoto, T. Nakamura, Y. Neo, H. Mimura, and M. Tomita, Graphene Simulation (InTech, Croatia, 2011), Chap. 8.

T. Hase, T. Kano, E. Nakazawa, and H. Yamamoto, Advances in Electronics and Electron Physics (Academic Press, New York, 1990), pp. 271–373.

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Figures (5)

Fig. 1
Fig. 1

The left inset displays a schematic of an AlxGa1-xN/AlN multiple quantum well structure grown on a c-plane sapphire substrate. The multiple quantum wells were composed of 10 periods of AlxGa1-xN/AlN layers with a stoichiometric x of 0.7. The AlxGa1-xN quantum wells and the AlN barrier layers were each 3 nm thick, yielding a 60-nm-thick quantum well region. The main figure shows a photoluminescence spectrum of the Al0.7Ga0.3N multiple quantum wells obtained at room temperature with an ArF excimer laser. The right inset shows an internal quantum efficiency curve as a function of carrier density obtained by the Shockley-Reed-Hall model. The dislocation density was assumed to be 1.8 × 108 cm−2 based on 2θ/ω-scan X-ray diffraction measurements.

Fig. 2
Fig. 2

Contour plots of the electron energy as a function of the Al0.7Ga0.3N multiple quantum well depth (the vertical direction) for (a) Va = 3 kV and (b) Va = 10 kV obtained by the Monte Carlo method. The purple region is the 60-nm-thick (10 periods) Al0.7Ga0.3N (3 nm)/AlN (3 nm) multiple quantum well layer, and the blue color region is the 15-μm-thick AlN layer. The radius of the incident electron beam is 10 nm. The percentages (degradation of the red color region) indicate the electron energy with respect to the initial value. (c) Cathodeluminescence spectrum as a function of the excitation energy of the electron beam for 3 keV (green line), 5 keV (blue line), and 10 keV (red line). The main emission peak at approximately 240 nm is the band-edge emission of the multiple quantum well layer, and the peak at approximately 210 nm observed for an excitation energy of 10 keV is the band-edge emission from the AlN layer. The broad emission at approximately 350 nm observed for all excitation energies is the deep level and/or defect state emission of the multiple quantum well layer, and the emission peak near 330 nm observed for an excitation energy of 10 keV is the defect state emission of the AlN layer. (d) Observed cathodeluminescence intensities (red circles: 1 nA, blue circles: 0.1 nA) as a function of incident electron energy. The dotted line is the theoretically obtained cathodeluminescence intensity as a function of incident electron energy, where the cathodeluminescence intensity is assumed to be proportional to the absorbed energy in the multiple quantum wells. The solid line is the theoretically fitted line for the results of the cathodeluminescence intensity as a function of incident electron energy based on the diffusion and trapping processes of excitons generated in the multiple quantum wells.

Fig. 3
Fig. 3

(a) Transmission electron microscopy image of a single graphene nanoneedle. (b) High-resolution transmission electron microscopy image of a single graphene nanoneedle. (c) Selected area electron diffraction pattern. Based on the spacing of the c-axis diffraction patterns, the structure of the needle was determined to be a two-dimensional graphene sheet with an interplanar spacing of 0.36 nm. Based on the spacing of the a-axis diffraction pattern, the (010) plane spacing based on a six-member ring was determined to be 0.21 nm.

Fig. 4
Fig. 4

(a) The deep ultraviolet emission tube is composed of a graphene nanoneedle cold cathode and an Al/AlGaN/AlN/sapphire deep ultraviolet emission target. The electrons emitted from the graphene nanoneedle cold cathode excite the AlGaN multiple quantum well layer, causing the multiple quantum wells to emit deep ultraviolet fluorescence. This deep ultraviolet emission is extracted through a sapphire window for which the back of the substrate (output side) is roughened by a mechanical process to enhance the deep ultraviolet emission extraction efficiency. (b) Lifetime test of the graphene nanoneedle cold cathode at a constant current of 500 μA. No degradation in the anode bias voltage is observed, and the lifetime of the graphene nanoneedle cold cathode exceeds 5,000 hours.

Fig. 5
Fig. 5

(a) Photograph of a battery-driven deep ultraviolet emission device. The power supply operated at a cathode voltage range of 0-10 kV and a cathode current range of 0-500 μA, which is obtained by using DC-DC converters driven with AA dry batteries in series. The dimensions of the deep ultraviolet tube and the power supply are 30φ × 60 mm and 100 mm × 35 mm × 150 mm, respectively, and the total weight of the deep ultraviolet light source with the power supply is approximately 650 g. (b) Photoluminescence image of a Y2O3:Eu phosphor irradiated by deep ultraviolet emission under a cathode voltage of 7.5 kV and a cathode current of 80 μA. The inset is a photoluminescence-excitation spectrum of the Y2O3:Eu phosphor, where absorption occurs from the shorter excitation wavelengths of less than 300 nm. The obtained power and efficiency are approximately 20 mW and 4%, respectively.

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