Abstract
P–n junction GaN light-emitting diodes (LEDs) were fabricated using Ga-doped ZnO (GZO) films as electrical contacts and characterized by electroluminescence (EL) and current–voltage (I–V) measurements. GaN p–n epilayers with a total thickness of ~6 μm were grown on c-plane (0001) sapphire substrates by metal–organic chemical vapor deposition. Half region of the p-GaN layer was etched until the n-GaN layer was exposed, and 100-nm-thick GZO contacts were deposited on the p- and n-GaN layers by RF sputtering with varying Ga concentration (n G ) from 1 to 5 mol%. Based on the results of Hall effect, photoluminescence (PL), and X-ray diffraction (XRD), the GZO films were expected to act as best electrical contacts for the LEDs at n G = 2 mol%. Under forward-bias conditions, the I–V curves showed diode characteristics except n G = 5 mol%, and the leakage current was minimized at n G = 2 mol%. Two dominant EL peaks of ultraviolet and yellow emissions were observed at ~376 and ~560 nm, and attributed to near-band-edge- and defect-related radiative transitions, respectively. At n G = 2 mol%, the UV EL showed markedly large intensities for all injection currents, consistent with the results of Hall effect, PL, I–V, and XRD.
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J.-K. Sheu, Y.S. Lu, M.-L. Lee, W.C. Lai, C.H. Kuo, C.-J. Tun, Appl. Phys. Lett. 90, 263511 (2007)
T. Minami, J. Vac. Sci. Technol. A 17, 1765 (1999)
J.H. Kim, K.A. Jeon, G.H. Kim, S.Y. Lee, Appl. Surf. Sci. 252, 4834 (2006)
T. Minami, Semicond. Sci. Technol. 20, S35 (2005)
V. Bhosle, A. Tiwari, J. Narayan, Appl. Phys. Lett. 88, 032106 (2006)
H. Kim, J.S. Horwitz, S.B. Qadri, D.B. Chrisey, Thin Solid Films 420–421, 107 (2002)
T.-Y. Park, Y.-S. Choi, J.-W. Kang, J.-H. Jeong, S.-J. Park, D.M. Jeon, J.W. Kim, Y.C. Kim, Appl. Phys. Lett. 96, 051124 (2010)
B.D. Ahn, J.H. Kim, H.S. Kang, C.H. Lee, S.H. Oh, K.W. Kim, G.-E. Jang, S.Y. Lee, Thin Solid Films 516, 1382 (2008)
D.K. Lee, S. Kim, M.C. Kim, S.H. Eom, H.T. Oh, S.-H. Choi, J. Korean Phys. Soc. 51, 1378 (2007)
H.J. Ko, Y.F. Chen, S.K. Hong, H. Wenisch, T. Yao, D.C. Look, Appl. Phys. Lett. 77, 3761 (2000)
X. Yu, J. Ma, F. Ji, Y. Wang, X. Zhang, C. Cheng, H. Ma, J. Cryst. Growth 274, 474 (2005)
K. Nakahara, K. Tamura, M. Sakai, D. Nakagawa, N. Ito, M. Sonobe, H. Takasu, H. Tampo, P. Fons, K. Matsubara, K. Iwata, A. Yamada, S. Niki, Jpn. J. Appl. Phys. 43, L180 (2004)
S.H. Tu, C.J. Lan, S.H. Wang, M.L. Lee, K.H. Chang, R.M. Lin, J.Y. Chang, J.K. Sheu, Appl. Phys. Lett. 96, 133504 (2010)
S. Chu, J.H. Lim, L.J. Mandalapu, Z. Yang, L. Li, J.L. Liu, Appl. Phys. Lett. 92, 152103 (2008)
B. Lin, Z. Fu, Y. Jia, Appl. Phys. Lett. 79, 943 (2001)
Z.Z. Zhi, Y.C. Liu, B.S. Li, X.T. Zhang, Y.M. Lu, D.Z. Shen, X.W. Fan, J. Phys. D 36, 719 (2003)
J.-K. Sheu, M.-L. Lee, Y.S. Lu, K.W. Shu, IEEE J. Quantum Electron. 44, 1211 (2008)
F. Wu, L. Fang, Y.J. Pan, K. Zhou, Q.L. Huang, C.Y. Kong, Phys. E 43, 228 (2010)
T. Omata, N. Ueda, K. Ueda, H. Kawazoe, Appl. Phys. Lett. 64, 1077 (1994)
I.E. Titkov, L.A. Delimova, A.S. Zubrilov, N.V. Seredova, I.A. Liniichuk, I.V. Grekhov, J. Mod. Opt. 56, 653 (2009)
R.L. Anderson, Solid-State Electron. 5, 341 (1962)
A. Behrends, A. Bakin, A. Waag, H.-S. Kwack, L.S. Dang, Phys. Stat. Sol. C 7, 1709 (2010)
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This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2011-0017373).
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Kim, C.O., Kim, S., Shin, D.H. et al. Effect of Ga doping concentration on the luminescence efficiency of GaN light-emitting diodes with Ga-doped ZnO contacts. Appl. Phys. B 109, 283–287 (2012). https://doi.org/10.1007/s00340-012-5129-z
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DOI: https://doi.org/10.1007/s00340-012-5129-z