Use of TiB 2 diffusion barriers for Ni/Au ohmic contacts on p-GaN

Lars Voss, Rohit Khanna, S. J. Pearton, F. Ren, I. I. Kravchenko

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11 Scopus citations

Abstract

The use of a TiB 2 diffusion barrier for Ni/Au contacts on p-GaN is reported. The annealing temperature (25-950 °C) dependence of ohmic contact characteristics using a Ni/Au/TiB 2 /Ti/Au metallization scheme deposited by sputtering were investigated by contact resistance measurements and auger electron spectroscopy (AES). The as-deposited contacts are rectifying and transition to ohmic behavior for annealing at ≥500 °C . A minimum specific contact resistivity of ∼3 × 10 -4 Ω cm -2 was obtained after annealing over a broad range of temperatures (800-950 °C for 60 s). The contact morphology became considerably rougher at the higher end of this temperature range. AES profiling showed significant Ti and Ni outdiffusion through the TiB 2 at 800 °C. By 900 °C the Ti was almost completely removed to the surface, where it became oxidized. Use of the TiB 2 diffusion barrier produces superior thermal stability compared to the more common Ni/Au, whose morphology degrades significantly above 500 °C.

Original languageEnglish
Pages (from-to)1255-1259
Number of pages5
JournalApplied Surface Science
Volume253
Issue number3
DOIs
StatePublished - Nov 30 2006
Externally publishedYes

Funding

The work at UF is partially supported by the Army Research Office under grant no. DAAD19-01-1-0603, NSF (CTS-0301178, monitored by Dr. M. Burka and Dr. D. Senich) and the National Science Foundation (DMR 0400416, Dr. L. Hess).

Keywords

  • Annealing
  • GaN
  • Ohmic contacts

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