Abstract
We report on a study of Al and Ti/Al contacts to n-type GaN. Al contacts on n-GaN (7 × 1017cm−3) annealed in forming gas at 600°C reached a minimum contact resistivity of 8×10≈6Ωcm2 and had much better thermal stability than reported by previous researchers. Ti/Al (35nm/115nm) contacts on n-GaN (5×1017cm−3) had resistivities of 7 × 10−6Ωcm2 and 5×10−6Ωcm2 after annealing in Ar at 400°C for 5min and 600°C for 15sec, respectively. Depth profiles of Ti/Al contacts annealed at 400°C showed that low contact resistance was only achieved after Al diffused to the GaN interface. We propose that the mechanism for ohmic contact formation in Ti/Al contacts annealed in the 400–600°C range includes reduction of the native oxide on GaN by Ti and formation of an Al-Ti intermetallic phase in intimate contact with the GaN. Contacts with different Ti/Al layer thicknesses were investigated and those with 50nm/100nm layers had the same low resistance and better stability than 25nm/125nm contacts.
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Z.-F. Fan, S. N. Mohammad, W. Kim, O. Aktas, A. E. Botchkarev and H. Morkoc, Appl. Phys. Lett. 68, 1672 (1996).
M. E. Lin, Z. Ma, F. Y. Huang, Z. F. Fan, L. H. Allen, and H. Morkoc, Appl. Phys. Lett. 64, 1003 (1994).
S. Ruvimov, Z. Liliental-Weber, J. Washburn, K. J. Duxstad, E. E. Haller, Z.-F. Fan, S. N. Mohammad, W. Kim, A. E. Botchkarev and H. Morkoc, Appl. Phys. Lett. 69, 1556 (1996).
A. T. Ping, M. Asif Khan, and I. Adesida, J. Electron. Mat. 25, 819 (1996).
G. S. Marlow and M. B. Das, Solid St. Electron. 25, 91 (1982).
S. P. Kowalczyk, J. R. Waldrop, and R. W. Grant, J. Vac. Sci. Technol. 19, 611 (1981).
K. W. Boer, Survey of Semiconductor Physics (Van Nostrand, New York, 1990).
J. I. Pankove and H. Schade, Appl. Phys. Lett. 25, 53 (1971).
J. S. Foresi and T. D. Moustakas, Appl. Phys. Lett. 62, 2859 (1993).
L. L. Smith, R. F. Davis, M. J. Kim, R. W. Carpenter and Y. Huang, J. Mater. Res. 11, 2257 (1996).
S. C. Binari, H. B. Dietrich, G. Kelner, L. B. Rowland, K. Doverspike, and D. K. Gaskill, Electron. Lett. 30, 909 (1994).
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Luther, B.P., Mohney, S.E., Jackson, T.N. et al. Investigation of Aluminum and Titanium/Aluminum Contacts to n-Type Gallium Nitride. MRS Online Proceedings Library 449, 1097–1102 (1996). https://doi.org/10.1557/PROC-449-1097
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DOI: https://doi.org/10.1557/PROC-449-1097