Development of ohmic contact materials for wide gap p-type 4H-SiC

Conventional TiAl ohmic contacts are annealed at a high temperature which caused extremely rough surface morphology. The objective of this paper is to reduce the annealing temperature of the ohmic contact formation by adding a thin Ni or Ge layer to the TiAl contacts. The microstructure analyses between the SiC and the Ti/Al, Ni/Ti/Al or Ge/Ti/Al contact materials were made using cross sectional high resolution transmission electron microscope. The interfacial microstructure analysis indicated that the reduction of the annealing temperature was obtained due to enhancement of the carbide layer formation by increasing the chemical reactivity between the SiC and the contact materials.