{"title":"Low resistivity Hf\/Al\/Ni\/Au Ohmic Contact Scheme to n-Type GaN","authors":"Y. Liu, M. K. Bera, L. M. Kyaw, G. Q. Lo, E. F. Chor","volume":69,"journal":"International Journal of Electrical and Computer Engineering","pagesStart":957,"pagesEnd":961,"ISSN":"1307-6892","URL":"https:\/\/publications.waset.org\/pdf\/6868","abstract":"The electrical and structural properties of Hf\/Al\/Ni\/Au\r\n(20\/100\/25\/50 nm) ohmic contact to n-GaN are reported in this study.\r\nSpecific contact resistivities of Hf\/Al\/Ni\/Au based contacts have been\r\ninvestigated as a function of annealing temperature and achieve the\r\nlowest value of 1.09\u00b410-6 \u03a9\u00b7cm2 after annealing at 650 oC in vacuum.\r\nA detailed mechanism of ohmic contact formation is discussed. By\r\nusing different chemical analyses, it is anticipated that the formation of\r\nHf-Al-N alloy might be responsible to form low temperature ohmic\r\ncontacts for the Hf-based scheme to n-GaN.","references":"[1] S. Nakamura, M. Senoh, S. Nagahama, N. Iwasa, T. Yamada, T.\r\nMatsushita, H. Kiyoku, Y. Sugimoto, T. Kozaki, H. Umemoto, M. Sano,\r\nand K. Chocho, \"Continuous-wave operation of\r\nInGaN\/GaN\/AlGaN-based laser diodes grown on GaN substrates,\"\r\nApplied Physics Letters, vol. 72, pp. 2014-2016, Apr 20 1998.\r\n[2] S. Nakamura, T. Mukai, and M. Senoh, \"Candela-Class High-Brightness\r\nIngan\/Algan Double-Heterostructure Blue-Light-Emitting Diodes,\"\r\nApplied Physics Letters, vol. 64, pp. 1687-1689, Mar 28 1994.\r\n[3] I. Vurgaftman and J. R. Meyer, \"Band parameters for nitrogen-containing\r\nsemiconductors,\" Journal of Applied Physics, vol. 94, pp. 3675-3696,\r\nSep 2003.\r\n[4] K. T. Lee, C. F. Huang, J. Gong, and C. T. Lee, \"High-Performance 1-mu\r\nm GaN n-MOSFET With MgO\/MgO-TiO(2) Stacked Gate Dielectrics,\"\r\nIeee Electron Device Letters, vol. 32, pp. 306-308, Mar 2011.\r\n[5] C. Y. Tsai, T. L. Wu, and A. Chin, \"High-Performance GaN MOSFET\r\nWith High-k LaAlO(3)\/SiO(2) Gate Dielectric,\" Ieee Electron Device\r\nLetters, vol. 33, pp. 35-37, Jan 2012.\r\n[6] S. Ruvimov, Z. Liliental-Weber, J. Washburn, K. J. Duxstad, E. E. Haller,\r\nZ. F. Fan, S. N. Mohammad, W. Kim, A. E. Botchkarev, and H. Morkoc*,\r\n\"Microstructure of Ti\/Al and Ti\/Al\/Ni\/Au Ohmic contacts for n-GaN,\"\r\nApplied Physics Letters, vol. 69, p. 1556, 1996.\r\n[7] D. F. Wang, S. W. Feng, C. Lu, A. Motayed, M. Jah, S. N. Mohammad, K.\r\nA. Jones, and L. Salamanca-Riba, \"Low-resistance Ti\/Al\/Ti\/Au\r\nmultilayer ohmic contact to n-GaN,\" Journal of Applied Physics, vol. 89,\r\npp. 6214-6217, Jun 1 2001.\r\n[8] D. Selvanathan, L. Zhou, V. Kumar, and I. Adesida, \"Low resistance\r\nTi\/Al\/Mo\/Au ohmic contacts for AlGaN\/GaN heterostructure field effect\r\ntransistors,\" Physica Status Solidi a-Applied Research, vol. 194, pp.\r\n583-586, Dec 16 2002.\r\n[9] S. Kurtin, T. C. McGill, and C. A. Mead, \"Fundamental transition in the\r\nelectronic nature of solids,\" Physical Review Letters, vol. 22, pp.\r\n1433-1436, 1969.\r\n[10] D. R. Lide, CRC handbook of chemistry and physics: CRC Pr I Llc,\r\npp.12-124, 2012.\r\n[11] A. C. Schmitz, A. T. Ping, M. A. Khan, Q. Chen, J. W. Yang, and I.\r\nAdesida, \"Metal contacts to n-type GaN,\" Journal of Electronic Materials,\r\nvol. 27, pp. 255-260, Apr 1998.\r\n[12] M.-S. Chung, W.-T. Lin, and J. R. Gong, \"Formation of Hf ohmic\r\ncontacts by surface treatment of n-GaN in KOH solutions,\" Journal of\r\nVacuum Science & Technology B: Microelectronics and Nanometer\r\nStructures, vol. 19, p. 1976, 2001.\r\n[13] N. Yafune, M. Nagamori, H. Chikaoka, F. Watanabe, K. Sakuno, and M.\r\nKuzuhara, \"Low-Resistivity V\/Al\/Mo\/Au Ohmic Contacts on\r\nAlGaN\/GaN Annealed at Low Temperatures,\" Japanese Journal of\r\nApplied Physics, vol. 49, p. 04DF10, 2010.\r\n[14] A. N. Bright, P. J. Thomas, M. Weyland, D. M. Tricker, C. J. Humphreys,\r\nand R. Davies, \"Correlation of contact resistance with microstructure for\r\nAu\/Ni\/Al\/Ti\/AlGaN\/GaN ohmic contacts using transmission electron\r\nmicroscopy,\" Journal of Applied Physics, vol. 89, p. 3143, 2001.\r\n[15] D. Holec, R. Rachbauer, L. Chen, L. Wang, D. Luef, and P. H. Mayrhofer,\r\n\"Phase stability and alloy-related trends in Ti-Al-N, Zr-Al-N and Hf-Al-N\r\nsystems from first principles,\" Surface & Coatings Technology, vol. 206,\r\npp. 1698-1704, Dec 25 2011.\r\n[16] H. Okamoto, \"Al-Hf (Aluminum-Hafnium),\" Journal of Phase Equilibria\r\n& Diffusion, vol. 27, pp. 538-539, 2006.\r\n[17] J. S. Kwak, S. E. Mohney, J. Y. Lin, and R. S. Kern, \"Low resistance\r\nAl\/Ti\/n-GaN ohmic contacts with improved surface morphology and\r\nthermal stability,\" Semiconductor Science and Technology, vol. 15, pp.\r\n756-760, Jul 2000.","publisher":"World Academy of Science, Engineering and Technology","index":"Open Science Index 69, 2012"}