[1] S. Kamiyama, M. Iwaya, S. Takanami, S. Terao, A. Miyazaki, H. Amano, I. Akasaki. UV light-emitting diode fabricated on hetero-ELO-grown Al_0.22Ga_0.78N with low dislocation density. Phys. Status Solidi A, 192, 296-300(2002).

[2] V. Adivarahan, S. Wu, A. Chitnis, R. Pachipulusu, V. Mandavilli, M. Shatalov, J. P. Zhang, M. Asif Khan, G. Tamulaitis, A. Sereika, I. Yilmaz, M. S. Shur, R. Gaska. AlGaN single-quantum-well light-emitting diodes with emission at 285  nm. Appl. Phys. Lett., 81, 3666-3668(2002).

[3] A. Chitnis, J. P. Zhang, V. Adivarahan, W. Shuai, J. Sun, M. Shatalov, J. W. Yang, G. Simin, M. A. Khan. 324 nm light emitting diodes with milliwatt powers. Jpn. J. Appl. Phys., 41, L450-L451(2002).

[4] H. Hirayama, Y. Enomoto, A. Kinoshita, A. Hirata, Y. Aoyagi. Efficient 230-280  nm emission from high-Al-content AlGaN-based multiquantum wells. Appl. Phys. Lett., 80, 37-39(2002).

[5] M. Iwaya, S. Takanami, A. Miyazaki, Y. Watanabe, S. Kamiyama, H. Amano, I. Akasaki. High-power UV-light-emitting diode on sapphire. Jpn. J. Appl. Phys., 42, 400-403(2003).

[6] H. Hirayama, T. Yatabe, N. Noguchi, T. Ohashi, 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, 071901(2007).

[7] Y. Taniyasu, M. Kasu, T. Makimoto. An aluminium nitride light-emitting diode with a wavelength of 210 nanometres. Nature, 441, 325-328(2006).

[8] K. Nagamatsu, N. Okada, H. Sugimura, H. Tsuzuki, F. Mori, K. Iida, A. Bando, M. Iwaya, S. Kamiyama, H. Amano, I. Akasakia. High-efficiency AlGaN-based UV light-emitting diode on laterally overgrown AlN. J. Cryst. Growth, 310, 2326-2329(2008).

[9] M. Kaneda, C. Pernot, Y. Nagasawa, A. Hirano, M. Ippommatsu, Y. Honda, H. Amano, I. Akasaki. Uneven AlGaN multiple quantum well for deep-ultraviolet LEDs grown on macrosteps and impact on electroluminescence spectral output. Jpn. J. Appl. Phys., 56, 061002(2017).

[10] C. Pernot, M. Kim, S. Fukahori, T. Inazu, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, S. Kamiyama, I. Akasaki, H. Amano. Improved efficiency of 255-280  nm AlGaN-based light-emitting diodes. Appl. Phys. Express, 3, 061004(2010).

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

[12] A. Fujioka, K. Asada, H. Yamada, T. Ohtsuka, T. Ogawa, T. Kosugi, D. Kishikawa, T. Mukai. High-output-power 255/280/310  nm deep ultraviolet light-emitting diodes and their lifetime characteristics. Semicond. Sci. Technol., 29, 084005(2014).

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

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

[15] K. Ban, J. Yamamoto, K. Takeda, K. Ide, M. Iwaya, T. Takeuchi, S. Kamiyama, I. Akasaki, H. Amano. Internal quantum efficiency of whole-composition-range AlGaN multiquantum wells. Appl. Phys. Express, 4, 052101(2011).

[16] H. Murotani, D. Akase, K. Anai, Y. Yamada, H. Miyake, K. Hiramatsu. Dependence of internal quantum efficiency on doping region and Si concentration in Al-rich AlGaN quantum wells. Appl. Phys. Lett., 101, 042110(2012).

[17] H. Yoshida, M. Kuwabara, Y. Yamashita, K. Uchiyama, H. Kan. Radiative and nonradiative recombination in an ultraviolet GaN/AlGaN multiple-quantum-well laser diode. Appl. Phys. Lett., 96, 211122(2010).

[18] M. Kneissl, J. Rass. III-Nitride UV Emitter: Technologies and Their Applications(2016).

[19] C. G. Moe, G. A. Garrett, J. R. Grandusky, J. Chen, L. E. Rodak, P. Rotella, M. Wraback, L. J. Schowalter. Correlation between optical and electrical performance of mid-ultraviolet light-emitting diodes on AlN substrates. Phys. Status Solidi, C11, 786-789(2014).

[20] Z. Bryan, I. Bryan, J. Xie, S. Mita, Z. Sitar, R. Collazo. High internal quantum efficiency in AlGaN multiple quantum wells grown on bulk AlN substrates. Appl. Phys. Lett., 106, 142107(2015).

[21] M. Shatalov, J. Yang, W. Sun, R. Kennedy, R. Gaska, K. Liu, M. Shur, G. Tamulaitis. Efficiency of light emission in high aluminum content AlGaN quantum wells. J. Appl. Phys., 105, 073103(2009).

[22] T. Inazu, S. Fukahori, C. Pernot, M. H. Kim, T. Fujita, Y. Nagasawa, A. Hirano, M. Ippommatsu, M. Iwaya, T. Takeuchi, S. Kamiyama, M. Yamaguchi, Y. Honda, H. Amano, I. Akasaki. Improvement of light extraction efficiency for AlGaN-based deep ultraviolet light-emitting diodes. Jpn. J. Appl. Phys., 50, 122101(2011).

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

[24] M. Shatalov, W. H. Sun, R. Jain, A. Lunev, X. H. Hu, A. Dobrinsky, Y. Bilenko, J. W. Yang, G. A. Garrett, L. E. Rodak, M. Wraback, M. Shur, R. Gaska. High power AlGaN ultraviolet light emitters. Semicond. Sci. Technol., 29, 084007(2014).

[25] K. Yamada, Y. Furusawan, S. Nagai, A. Hirano, M. Ippommatsu, K. Aosaki, N. Morishima, H. Amano, I. Akasaki. Development of underfilling and encapsulation for deep-ultraviolet LEDs. Appl. Phys. Express, 8, 012101(2015).

[26] M. Ichikawa, A. Fujioka, T. Kosugi, S. Endo, H. Sagawa, H. Tamaki, T. Mukai, M. Uomoto, T. Shimatsu. High-output-power deep ultraviolet light-emitting diode assembly using direct bonding. Appl. Phys. Express, 9, 072101(2016).

[27] S. Nagai, K. Yamada, A. Hirano, M. Ippommatsu, M. Ito, N. Morishima, K. Aosaki, Y. Honda, H. Amano, I. Akasaki. Development of highly durable deep-ultraviolet AlGaN-based LED multichip array with hemispherical encapsulated structures using a selected resin through a detailed feasibility study. Jpn. J. Appl. Phys., 55, 082101(2016).

[28] . Nichia(2018). http://www.nichia.co.jp/jp/product/uvled.html

[29] K. Yamada, Y. Nagasawa, S. Nagai, A. Hirano, M. Ippommatsu, K. Aosaki, Y. Honda, H. Amano, I. Akasaki. Study on the main-chain structure of amorphous fluorine resins for encapsulating AlGaN-based DUV-LEDs. Phys. Status Solidi, A215, 1700525(2018).

[30] J. Wu. High power high efficiency DUV-LEDs and applications(2016).

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

[32] http://www.chem.tamu.edu/rgroup/connell/linkfiles/bonds.pdf. http://www.chem.tamu.edu/rgroup/connell/linkfiles/bonds.pdf

[33] http://www.geocities.jp/toyookawase/30ketugoue.pdf. http://www.geocities.jp/toyookawase/30ketugoue.pdf

[34] K. Nakamura, N. Sugiyama, Y. Etoh, K. Aosaki, J. Endo. Development of perfluoro transparent resins obtained by radical cyclopolymerization for leading-edge electronic and optical applications. Nippon Kagaku Kaishi, 12, 659(2001).

[35] I. Blakey, G. A. George, D. J. T. Hill, H. P. Liu, F. Rasoul, A. K. Whittaker, P. Zimmerman. XPS and ¹⁹F NMR study of the photodegradation at 157 nm of photolithographic-grade teflon AF thin films. Macromolecules, 38, 4050-4053(2005).

[36] K. Yamamoto, G. Ogawa. Structure determination of the amorphous perfluorinated homopolymer: poly[perfluoro(4-vinyloxyl-1-butene)]. J. Fluorine Chem., 126, 1403-1408(2005).

[37] A. Hirano, Y. Nagasawa, M. Ippommatsu, K. Aosaki, Y. Honda, H. Amano, I. Akasaki. Development of AlGaN-based deep-ultraviolet (DUV) LEDs focusing on the fluorine resin encapsulation and the prospect of the practical applications. Proc. SPIE, 9926, 99260C(2016).

[38] W. K. Fisher, J. C. Correlli. Effect of ionizing radiation on the chemical composition, crystalline content and structure, and flow properties of polytetorafluoroethylene. J. Polymer Sci., 19, 2465-2493(1981).

[39] T. R. Dargaville, G. A. George, D. J. T. Hill, U. Scheler, A. K. Whittaker. Cross-linking of PFA by electron beam irradiation. Molecules, 36, 7138-7142(2003).

[40] J. Pacansky, R. J. Waltman, D. Jebens. Electron beam irradiation of a perfluoroalkoxy fluorocarbon resin: tetorafluoroethylene/perfluoromethyl vinyl ether copolymer. Molecules, 29, 7699-7704(1996).

[41] P. Yang, X. Guo, R. Liang, H. Cheng, M. Chen. Enhanced light extraction from DUV-LEDs by AlN-doped fluoropolymer encapsulation. IEEE Photon. Lett., 29, 1151-1154(2017).

[42] K. Aosaki. personal communication.

[43] https://www.nikkiso.co.jp/technology/project/duv-led.html#ac02. https://www.nikkiso.co.jp/technology/project/duv-led.html#ac02

[44] https://www.klaran.com/products/uvc-leds/klaran-gd-series. https://www.klaran.com/products/uvc-leds/klaran-gd-series

[45] Y. Peng, S. Wang, H. Cheng, M. Chen. Whole inorganic hermetic packaging technology using localized induction heating for deep ultraviolet light-emitting diodes. IEEE Trans. Compon., 6, 1456-1461(2016).

[46] Y. Pai, C. Lin, C. Lee, C. Lin, C. Chen, H. Kuo, Z. Ye. Enhancing the light-extraction efficiency of AlGaN-based deep-ultraviolet light-emitting diodes by optimizing the diameter and tilt of the aluminum sidewall. Crystals, 8, 420(2018).

[47] Y. Hatanaka, M. Ito, Y. Sakane, Y. Nagasawa, A. Hirano, M. Ippommatsu. Demonstration of mass production techniques at feasible cost for surface mount device of AlGaN-based DUV-LED with fluoro-resin encapsulation. International Workshop on Nitride Semiconductors, TuP-OD-2(2018).