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

doi:10.1063/1.119305

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 language	English (US)
Pages (from-to)	57-59
Number of pages	3
Journal	Applied Physics Letters
Volume	70
Issue number	1
DOIs	https://doi.org/10.1063/1.119305
State	Published - Jan 6 1997

All Science Journal Classification (ASJC) codes

Physics and Astronomy (miscellaneous)

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10.1063/1.119305

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

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.",

author = "Luther, {B. P.} and Mohney, {S. E.} and Jackson, {T. N.} and {Asif Khan}, M. and Q. Chen and Yang, {J. W.}",

year = "1997",

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doi = "10.1063/1.119305",

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T1 - Investigation of the mechanism for Ohmic contact formation in Al and Ti/Al contacts to n-type GaN

AU - Luther, B. P.

AU - Mohney, S. E.

AU - Jackson, T. N.

AU - Asif Khan, M.

AU - Chen, Q.

AU - Yang, J. W.

PY - 1997/1/6

Y1 - 1997/1/6

N2 - 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.

AB - 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.

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JO - Applied Physics Letters

JF - Applied Physics Letters

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

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