Ohmic contacts to Si-implanted and un-implanted n-type GaN

Abstract

We report on ohmic contacts to Si-implanted and un-implanted n-type GaN on sapphire. A ring shaped contact design avoids the need to isolate the contact structures by additional implantation or etching. Metal layers of Al and Ti/Al were investigated. On un-implanted GaN, post metalization annealing was performed in an RTA for 30 seconds in N2 at temperatures of 700, 800, and 900°C, A minimum specific contact resistance (rc) of 1.4×10−5 Ω-cm2 was measured for Ti/Al at an annealing temperature of 800°C. Although these values are reasonably low, variations of 95% in specific contact resistance were measured within a 500 µm distance on the wafer. These results are most likely caused by the presence of compensating hydrogen. Specific contact resistance variation was reduced from 95% to 10% by annealing at 900°C prior to metalization. On Si-implanted GaN, un-annealed ohmic contacts were formed with Ti/Al metalization. The implant activation anneal of 1120°C generates nitrogen vacancies that leave the surface heavily n-type, which makes un-annealed ohmic contacts with low contact resistivity possible.

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References

  1. 1

    C.P. Foley and T.L. Tansley, Phys. Rev. B, 33, No.2, 1430 (1986)

    CAS  Article  Google Scholar 

  2. 2

    J. S. Foresi, and T. D. Moustakas, Appl. Phys. Lett. 62, 2859 (1993).

    CAS  Article  Google Scholar 

  3. 3

    M.E. Lin, Z. Ma, F. Y. Huang, Z. F. Fan, L. H. Allen, and H. Morkoc, Appl. Phys. Lett. 64, 1003 (1994).

    CAS  Article  Google Scholar 

  4. 4

    S.C. Binari, H. B. Dietrich, G. Keiner, L. B. Rowland, K. Doverspike, and D. K. Gaskill, Electron. Lett. 30, 909 (1994).

    CAS  Article  Google Scholar 

  5. 5

    G. S. Marlow and M. B. Das, Solid St. Electron. 25, 91 (1982).

  6. 6

    S. D. Hersee, J. Ramer, K. Zheng, C. Kranenberg, K. Malloy, M. Banas, and M. Goorsky, to be published in J. Of Electronic Materials, November 1995.

    CAS  Article  Google Scholar 

  7. 7

    J.A. Van Vechten, J. D. Zook, R. D. Horning, and B. Goldenberg, Jpn. J. Appl. Phys. 31, 3662 (1992).

    Article  Google Scholar 

  8. 8

    S. Nakamura, N. Iwasa, M. Senoh, and T. Mukai, Jpn. J. Appl. Phys. 31, L1258 (1992).

    Google Scholar 

  9. 9

    J. D. Fast, Interaction of Metals and Gases, MacMillan, New York, 1971, Chapter 1.

    CAS  Article  Google Scholar 

  10. 10

    C. J. Sun, P. Kung, A. Saxler, H. Ohsato, E. Bigan, M. Razeghi, and D. K. Gaskill, J. Appl. Phys. 76, 236 (1994).

    Article  Google Scholar 

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Correspondence to J. Brown.

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Brown, J., Ramer, J., ZHeng, K. et al. Ohmic contacts to Si-implanted and un-implanted n-type GaN. MRS Online Proceedings Library 395, 855–860 (1995). https://doi.org/10.1557/PROC-395-855

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