Asuka E. Nomura

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Silicon Carbide with its wide bandgap, high thermal conductivity, and high breakdown electric field is an attractive material to be used for applications in high power, and high temperature semiconductor devices. For such applications, it is extremely important to be able to form stable ohmic contacts. Various metals have been attempted to form ohmic contacts on SiC such as Ni, Ti, and Al. However it has been observed that these metallization schemes have degraded performance due to carbon accumulation by forming carbides at the interface. In this study, polycide (poly Si + silicide) based metallizations have been investigated, using NiSi2 and TiSi2. Silicides of Ni and Ti have been synthesized employing a layer of heavily doped polysilicon to prevent any form of reaction between the metal and the carbon at the SiC interface. Using a 0.5cm2 n-type 6H-SiC samples with various doping concentrations (1.3 x 1018 cm-3 and 1.7 x 1018 cm-3), the electrical and structural properties of NiSi2 and TiSi2 have been examined by fabricating linear transmission line model (TLM) structures. I-V characterization have been carried out to determine the specific contact resistivity, PC. Samples were processed at various annealing temperatures to determine conditions for the best ohmic contact resistivity.

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