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Ohmic contacts and schottky barriers to n-GaN

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Abstract

Gallium nitride is a highly promising wide bandgap semiconductor with applications in high power electronic devices and optoelectronic devices. For these devices to be realized, metallization, both ohmic and rectifying must be available. In this manuscript, we discuss the properties of ohmic contacts and Schottky barriers on n-type GaN. The most recent ohmic metallization scheme involves TV Al based composites, namely Ti/Al/Ni/Au (150Å/2200Å/400Å/500Å) preceded by a reactive ion etching (RIE) process which most likely renders the surface highly n-type. With annealing at 900°C for 30 s, contacts with specific resistivity values less than ps= 1 x 10-7 Ω cm2 for a doping level of 4 x 1017 cm-3 were obtained. Schottky barriers with Ti, Cr, Pd, Au, Ni, and Pt have been reported; however, we will concentrate here on Pt based structures as they yield a large barrier height of 1.1 eV. Both capacitance-voltage and current-voltage analyses have been carried out as a function of temperature to gain insight into the current conduction processes involved. Attention must now be turned to the modifications needed to render these contacts reliable.

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Authors and Affiliations

  1. Materials Research Laboratory & Coordinated Science Laboratory, University of Illinois at Urbana-Champaign, 104 S. Goodwin Ave., 61801, Urbana, IL

    Z. Fan, S. N. Mohammad, W. Kim, Ö. Aktas, A. E. Botchkarev, K. Suzue & H. Morkoc

  2. Department of Materials Science and Lawrence Berkeley National Laboratory, University of California, 94720, Berkeley, CA

    K. Duxstad & E. E. Haller

Authors
  1. Z. Fan
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  2. S. N. Mohammad
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  3. W. Kim
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  4. Ö. Aktas
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  5. A. E. Botchkarev
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  6. K. Suzue
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  7. H. Morkoc
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  8. K. Duxstad
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  9. E. E. Haller
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Additional information

On sabbatical at Wright Laboratory under URRP program funded by AFOSR.

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Fan, Z., Mohammad, S.N., Kim, W. et al. Ohmic contacts and schottky barriers to n-GaN. J. Electron. Mater. 25, 1703–1708 (1996). https://doi.org/10.1007/s11664-996-0025-0

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  • DOI: https://doi.org/10.1007/s11664-996-0025-0

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