Abstract
A ray tracing model is developed to study the light extraction efficiency (LEE) of the nitride wide band gap semiconductor deep ultraviolet light emitting diodes (DUV-LEDs). The basic device structure is flip-chip LED device with dome shape encapsulation. Various device parameters such as reflecting p-metal, absorption coefficient of the AlN layer, sapphire surface roughness etc have been examined. We have found that the transparency of the AlGaN/AlN epitaxial layers as well as the encapsulation material play key roles in improving the LEE and spatial intensity distribution. To verify the transparency of the epi-layers, highly doped n-type Al\(_{0.61}\)Ga\(_{0.39}\)N on AlN template are grown on sapphire substrate by high-temperature metalorganic chemical vapor deposition (HT-MOCVD), then the crystal and optical properties are measured and analyzed. The calculated the absorption coefficient of the AlN is below 10\(^{3}\)cm\(^{-1}\), which paves the way to achieve high extraction efficiency DUV LEDs.
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Aurelien, D.: Surface-roughened light-emitting diodes: an accurate model. J. Display Technol. 9(5), 301–316 (2013)
Bae, J., Kim, Y.H., Kim, H.Y., Kim, Y.B., Jin, J.: Ultraviolet light stable and transparent sol-gel methyl siloxane hybrid material for UV light-emitting diode (UV LED) encapsulant. ACS Appl. Mater. Interfaces 7, 1035–1039 (2015)
Banal, R.G., Funato, M., Kawakami, Y.: Optical anisotropy in [0001]-oriented AlxGa1-xN/AlN quantum wells (x>0.69). Phys. Rev. B 79, 121308 (2009)
Bruce, W., Stephen, R.M., Hongsong, L., Kenneth, E.T.: Microfacet models for refraction through rough surfaces. In: Euro-Graphics Symposium on Rendering EGSR'07, pp. 195–206 (2007)
Cook, R., Torrance, K.: A Reflectance Model for Computer Graphics. ACM Trans. Gr. 1, 7–24 (1982)
Demiryont, H., Thompson, L.R., Collins, G.J.: Optical properties of aluminum oxynitrides deposited by laser-assisted CVD. Appl. Opt. 25, 1311–1318 (1986)
Dong, P., Yan, J., Zhang, Y., Wang, J., Zeng, J., Geng, C., Cong, P., Sun, L., Wei, T., Zhao, L., Yan, Q., He, C., Qin, Z.: AlGaN-based deep ultraviolet light-emitting diodes grown on nano-patterned sapphire substrates with significant improvement in internal quantum efficiency. J. Cryst. Growth 395, 9–13 (2014)
Grandusky, J.R., Gibb, S.R., Mendrick, M.C., Moe, C., Wraback, M., Schowalter, L.J.: High output power from 260 nm pseudomorphic ultraviolet light-emitting diodes with improved thermal performance. Appl. Phys. Express 4, 082101 (2011)
Hirano, A., Nagasawa, Y., Ippommatsu, M., Aosaki, K., Honda, Y., Amano, H., Akasaki, I.: Development of AlGaN-based deep-ultraviolet (DUV) LEDs focusing on the fluorine resin encapsulation and the prospect of the practical applications. Proceedings of SPIE, 9926, 99260 (2016)
Huang, S.-H., Horng, R.-H., Wen, K.-S., Lin, Y.-F., Yen, K.-W., Wuu, D.-S.: Improved light extraction of nitride-based flip-chip light-emitting diodes via sapphire shaping and texturing. IEEE Photon. Technol. Lett. 18(24), 2623–2625 (2006)
Hwang, S., Morgan, D., Kesler, A., Lachab, M., Zhang, B., Heidari, A., Nazir, H., Ahmad, I., Dion, J., Fareed, Q.: 276 nm substrate-free flip-chip AlGaN light-emitting diodes. Appl. Phys. Express 4, 032102 (2011)
Inoue, S.-I., Naoki, T., Kinoshita, T., Obata, T., Yanagi, H.: Light extraction enhancement of 265 nm deep-ultraviolet light-emitting diodes with over 90 mW output power. Appl. Phys. Lett. 106, 131104 (2015)
Khan, M.A., Shatalov, M., Maruska, H.P., Wang, H.M., Kuokstis, E.: III-nitride UV devices. Jpn. J. Appl. Phys. 44, 7191–7206 (2005)
Lee, Y.J., Hsu, T.C., Kuo, H.C., Wang, S.C., Yang, Y.L., Yen, S.N., Chu, Y.T., Shen, Y.J., Hsieh, M.H., Jou, M.J., Lee, B.J.: Improvement in light-output efficiency of near-ultraviolet InGaN-GaN LEDs fabricated on stripe patterned sapphire substrates. Mater. Sci. Eng. B 122, 184–187 (2005)
Lu, P., Collazo, R., Dalmau, R.F., Durkaya, G., Dietz, N., Sitar, Z.: Different optical absorption edges in AlN bulk crystals grown in m- and c-orientations. Appl. Phys. Lett. 93, 131922 (2008)
Nam, K.B., Li, J., Nakarmi, M.L., Lin, J.Y., Jianga, H.X.: Unique optical properties of AlGaN alloys and related ultraviolet emitters. Appl. Phys. Lett. 84, 5264–5266 (2004)
Northrup, J.E., Chua, C.L., Yang, Z., Wunderer, T., Kneissl, M., Johnson, N.M., Kolbe, T.: Effect of strain and barrier composition on the polarization of light emission from AlGaN/AlN quantum wells. Appl. Phys. Lett. 100, 021101 (2012)
Oren, M., Nayar, S.: Generalization of Lambert's reflectance model. In: SIGGRAPH’94 Proceedings, pp. 239–246 (1994)
Phong, B.T.: Illumination for computer generated pictures. In: Conference Proceedings, vol. 6, pp. 311–317. ACM Press (1975)
Rakić, A.D.: Algorithm for the determination of intrinsic optical constants of metal films: application to aluminum. Appl. Opt. 34, 4755–4767 (1995)
Shatalov, M., Sun, W., Lunev, A., Xuhong, H., Dobrinsky, A., Bilenko, Y., Yang, J., Shur, M., Gaska, R., Moe, C., Garrett, G., Wraback, M.: AlGaN Deep-Ultraviolet Light-Emitting Diodes with External Quantum Efficiency above 10%. Appl. Phys. Epress 5, 082101 (2012)
Taniyasu, Y., Kasu, M.: Polarization property of deep-ultraviolet light emission from C-plane AlN/GaN short-period superlattices. Appl. Phys. Lett. 99, 251112 (2011)
Tomiya, S., Kanitani, Y., Tanaka, S., Ohkubo, T., Hono, K.: Atomic scale characterization of GaInN/GaN multiple quantum wells in V-shaped pits. Appl. Phys. Lett. 98, 181904 (2011)
Weaver, J.H., Olson, C.G., Lynch, D.W.: Optical investigation of the electronic structure of bulk Rh and Ir. Phys. Rev. B 15, 4115–4118 (1977)
Werner, W.S.M., Glantschnig, K., Ambrosch-Draxl, C.: Optical constants and inelastic electron-scattering data for 17 elemental metals. J. Phys. Chem. Ref. 38, 1013–1092 (2009)
Windisch, R., Rooman, C., Dutta, B., Knobloch, A., Borghs, G., Dohler, G.H., Heremans, P.: Light-extraction mechanisms in high-efficiency surface-textured light-emitting diodes. Top. Quantum Electron. 8(2), 248–255 (2002)
Yan, Q., Janotti, A., Scheffler, M., VandeWalle, C.G.: Origins of optical absorption and emission lines in AlN. Appl. Phys. Lett. 105, 111104 (2014)
Yan, J., Wang, J., Zhang, Y., Cong, P., Sun, L., Tian, Y., Zhao, C., Li, J.: AlGaN-based deep-ultraviolet light-emitting diodes grown on high-quality AlN template using MOVPE. J. Cryst. Growth 414, 254–257 (2015)
Ying, X., Feldman, A., Farabaugh, E.N.: Fitting of transmission data for determining the optical constants and thicknesses of optical films. J. Appl. Phys. 67, 2056–2059 (1990)
Yong, A.M., Soh, C.B., Zhang, X.H., Chow, S.Y., Chua, S.J.: Investigation of V-defects formation in InGaN/GaN multiple quantum well grown on sapphire. Thin Solid Films 515, 4496–4500 (2007)
Zarwasch, R., Rille, E., Pulker, H.K.: Fundamental optical absorption edge of reactively direct current magnetron sputter-deposited AlN thin films. J. Appl. Phys. 71, 5275–5277 (1992)
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The authors from Southeast University would like to thank the research funding from Suzhou Industrial Park District (Funding Number 7760890012).
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Fan, Q., Ni, X., Hua, B. et al. Extraction efficiency simulation in deep ultraviolet AlGaN light emitting diodes. Opt Quant Electron 53, 401 (2021). https://doi.org/10.1007/s11082-021-03043-2
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DOI: https://doi.org/10.1007/s11082-021-03043-2