Ti thickness influence for Ti/Ni ohmic contacts on n-type 3C-SiC

摘要

We report on the influence of titanium thickness on the structural and electrical properties of annealed Ti/Ni ohmic contacts on highly doped n-type 3C-SiC. Electrical analysis by means of circular transfer length method demonstrate that an interlayer of titanium with thickness in the range of 25-150 nm has no significant influence on specific contact resistance. However, from a structural point of view, the formation of nickel silicides as well as Ti_3SiC_2 is severely affected by the titanium thickness. Moreover, the Kirkendall effect due to the reaction between Ni and SiC is influenced by the titanium thickness. In fact, Scanning Electron Microscopy analysis demonstrates that the adjunction of titanium affects the distribution of Kirkendall voids in the contact. Current maps determined by conductive Atomic Force Microscopy reveal significant variation of uniformity according to the titanium thickness.