Abstract
The use of a TiB 2 diffusion barrier for Ni/Au contacts on p-GaN is reported. The annealing temperature (25-950 °C) dependence of ohmic contact characteristics using a Ni/Au/TiB 2 /Ti/Au metallization scheme deposited by sputtering were investigated by contact resistance measurements and auger electron spectroscopy (AES). The as-deposited contacts are rectifying and transition to ohmic behavior for annealing at ≥500 °C . A minimum specific contact resistivity of ∼3 × 10 -4 Ω cm -2 was obtained after annealing over a broad range of temperatures (800-950 °C for 60 s). The contact morphology became considerably rougher at the higher end of this temperature range. AES profiling showed significant Ti and Ni outdiffusion through the TiB 2 at 800 °C. By 900 °C the Ti was almost completely removed to the surface, where it became oxidized. Use of the TiB 2 diffusion barrier produces superior thermal stability compared to the more common Ni/Au, whose morphology degrades significantly above 500 °C.
Original language | English |
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Pages (from-to) | 1255-1259 |
Number of pages | 5 |
Journal | Applied Surface Science |
Volume | 253 |
Issue number | 3 |
DOIs | |
State | Published - Nov 30 2006 |
Externally published | Yes |
Funding
The work at UF is partially supported by the Army Research Office under grant no. DAAD19-01-1-0603, NSF (CTS-0301178, monitored by Dr. M. Burka and Dr. D. Senich) and the National Science Foundation (DMR 0400416, Dr. L. Hess).
Keywords
- Annealing
- GaN
- Ohmic contacts