Ohmic contacts to GaN with rapid thermal annealing

L. W. Chi; Kin Tak Lam; Y. K. Kao; Fuh-Shyang Juang; Y. S. Tasi; Yan-Kuin Su; Shoou-Jinn Chang; C. C. Chen; J. K. Sheu

doi:10.1117/12.382834

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17 April 2000 Ohmic contacts to GaN with rapid thermal annealing

L. W. Chi, Kin Tak Lam, Y. K. Kao, Fuh-Shyang Juang, Y. S. Tasi, Yan-Kuin Su, Shoou-Jinn Chang, C. C. Chen, J. K. Sheu

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Proceedings Volume 3938, Light-Emitting Diodes: Research, Manufacturing, and Applications IV; (2000) https://doi.org/10.1117/12.382834
Event: Symposium on Integrated Optoelectronics, 2000, San Jose, CA, United States

Abstract

This research attempted to use metals with lower work functions, such as Ti, Al, to form ohmic contacts to n-GaN. Then we used metals with higher work functions, such as Ni, Pd, Pt, and Au to form ohmic contacts to p-GaN. The work functions of these metals indeed influence the performance of ohmic contacts, indicating that the Fermi level of GaN is unpinned. The specific contact resistance measured and calculated by TCL model, was 2.35 X 10^-3 (Omega) cm² for as-deposited Ti/Al on GaN. After RTA processes at different temperatures in the range of 400 to approximately 900 degrees Celsius, the minimum (rho) _c of 7.4 X 10^-5 (Omega) cm² can be obtained for RTA temperature of 600 degrees Celsius. The oxidized Ni/Au contact exhibited the lowest contact resistance of 1.02 X 10^-2 (Omega) cm², among Ni/Au, Pd/Au, Pt/Au contact schemes on p-GaN. It was also observed that the I-V curves of the triple-layer contact, Pt/Ni/Au, was near-linear while the others were rectifying even after annealing.

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L. W. Chi, Kin Tak Lam, Y. K. Kao, Fuh-Shyang Juang, Y. S. Tasi, Yan-Kuin Su, Shoou-Jinn Chang, C. C. Chen, and J. K. Sheu "Ohmic contacts to GaN with rapid thermal annealing", Proc. SPIE 3938, Light-Emitting Diodes: Research, Manufacturing, and Applications IV, (17 April 2000); https://doi.org/10.1117/12.382834

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