Improved Thermal Stability Observed in Ni-Based Ohmic Contacts to n-Type SiC for High-Temperature Applications

• The high-temperature stability of a Pt/TaSi2/Ni/SiC ohmic contact metallization scheme was characterized using a combination of current-voltage measurements, Auger electron spectroscopy, and transmission electron microscopy imaging and associated analytical techniques. Increasing the thicknesses of the Pt and TaSi2 layers promoted electrical stability of the contacts, which remained ohmic at 600A degrees C in air for the extent of heat treatment; the specific contact resistance showed only a gradual increase from an initial value of 5.2 x 10(-5) Omega cm(2). We observed a continuous silicon oxide layer in the thinner contact structures, which failed after 36 h of heating. Meanwhile, thicker contacts with enhanced stability contained a much lower oxygen concentration that was distributed across the contact layers, precluding the formation of an electrically insulating contact structure.

Nyckelord

Ohmic contacts

silicon carbide

high-temperature reliability

scanning electron microscopy

transmission electron microscopy

TECHNOLOGY

TEKNIKVETENSKAP

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