Study of contact resistivity, mechanical integrity, and thermal stability of Ti/Al and Ta/Al ohmic contacts to n-type GaN

B. P. Luther, S. E. Mohney, J. M. Delucca, R. F. Karlicek

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

The annealing conditions and contact resistivities of Ta/Al ohmic contacts to n-type GaN are reported for the first time. The high temperature stability and mechanical integrity of Ti/Al and Ta/Al contacts have been investigated. Ta/Al (35 nm/115 nm) contacts to n-type GaN became ohmic after annealing for 3 min at 500°C or for 15 s at 600°C. A minimum contact resistivity of 5 × 10-6 Ω cm2 was measured after contacts were repatterned with an Al layer to reduce the effect of a high metal sheet resistance. Ti/Al and Ta/Al contacts encapsulated under vacuum in quartz tubes showed a significant increase in contact resistivity after aging for five days at 600°C. Cross section transmission electron microscopy micrographs and electrical measurements of aged samples indicate that the increased contact resistivity is primarily the result of degradation of the metal layers. Minimal reactions at the metal/GaN interface of aged samples were observed.

Original languageEnglish (US)
Pages (from-to)196-199
Number of pages4
JournalJournal of Electronic Materials
Volume27
Issue number4
DOIs
StatePublished - Apr 1998

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

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