Investigation of aluminum and titanium/aluminum contacts to n-type gallium nitride

B. P. Luther, Suzanne E. Mohney, Thomas Nelson Jackson, M. A. Khan, Q. Chen, J. W. Yang

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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 × 10-6 Ωcm2 and had much better thermal stability than reported by previous researchers. Ti/Al (35nm/115nm) contacts on n-GaN (5 × l017cm-3) had resistivities of 7 × l0-6 Ωcm2 and 5 × 10-6 Ωcm2 after annealing in Ar at400°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.

Original languageEnglish (US)
Pages (from-to)1097-1102
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume449
StatePublished - Jan 1 1997
EventProceedings of the 1996 MRS Fall Symposium - Boston, MA, USA
Duration: Dec 2 1996Dec 5 1996

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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