Abstract
We have investigated Nb single and Nb/Au metallization schemes for the formation of thermally stable ohmic contacts to p-GaN. It is shown that the asdeposited Nb and Nb/Au contacts exhibit rectifying behavior. However, both the contacts produce ohmic characteristics when annealed at 850°C. Measurements show that the 850°C Nb/Au and Nb contacts yield a specific contact resistance of 1.9×10−8 and 2×10−2 ωcm2, respectively. Schottky barrier heights are found to decrease with increasing annealing temperature. A comparison of the XRD and electrical results shows that the formation of gallide phases such as Ga-Nb and Ga-Au compounds, play a role in forming ohmic contacts. Atomic force microscopy results show that the surface morphology of the Nb contacts is fairly stable up to 850°C, while the Nb/Au contacts are slightly degraded upon annealing at 850°C.
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Kim, HK., Seong, TY. & Lee, CR. Thermally stable Nb and Nb/Au ohmic contacts to p-GaN. J. Electron. Mater. 30, 266–270 (2001). https://doi.org/10.1007/s11664-001-0027-x
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DOI: https://doi.org/10.1007/s11664-001-0027-x