Investigation of the mechanism for Ohmic contact formation in Al and Ti/Al contacts to n-type GaN

B. P. Luther, S. E. Mohney, T. N. Jackson, M. Asif 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 × 1017 cm-3) annealed in forming gas at 600°C reached a minimum contact resistivity of 8 × 10-6 Ω cm2 and had much better thermal stability than reported by previous researchers. Ti/Al (35/115 nm) contacts on n-GaN (5 × 1017 cm-3) had resistivities of 7 × 10-6 and 5 × 10-6 Ω cm2 after annealing in Ar at 400°C for 5 min and 600°C for 15 s, 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 Ti reducing the GaN native oxide and an Al-Ti intermetallic coming into intimate contact with the GaN.

Original languageEnglish (US)
Pages (from-to)57-59
Number of pages3
JournalApplied Physics Letters
Volume70
Issue number1
DOIs
Publication statusPublished - Jan 6 1997

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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