Investigation of Thermal Stability and Degradation
Mechanisms in Ni-Based Ohmic Contacts to <Emphasis Type="Italic">n</Emphasis>-Type
SiC for High-Temperature Gas Sensors |
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Authors: | Ariel Virshup Lisa M Porter Dorothy Lukco Kristina Buchholt Lars Hultman Anita Lloyd Spetz |
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Affiliation: | 1.Carnegie Mellon University,Pittsburgh,USA;2.ASRC Aerospace Corporation,Clevelang,USA;3.Link?ping University,Link?ping,Sweden |
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Abstract: | We investigated the thermal stability of Pt/TaSi
x
/Ni/SiC ohmic contacts, which have been implemented in SiC-based gas sensors developed for applications in diesel engines
and power plants. The contacts remained ohmic on lightly doped n-type (~1 × 1016 cm−3) 4H-SiC for over 1000 h in air at 300°C. Although a gradual increase in specific contact resistance from 3.4 × 10−4 Ω cm2 to 2.80 × 10−3 Ω cm2 was observed, the values appeared to stabilize after ~800 h of heating in air at 300°C. The contacts heated at 500°C and
600°C, however, showed larger increases in specific contact resistance followed by nonohmic behavior after 240 h and 36 h,
respectively. Concentration profiles from Auger electron spectroscopy and electron energy-loss spectroscopy show that loss
of ohmic behavior occurs when the entire tantalum silicide layer has oxidized. |
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Keywords: | Ohmic contacts nickel contacts semiconductor contacts SiC contacts degradation mechanism stability reliability |
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