Ultra-Thin Epitaxial Tungsten Carbide Schottky Contacts in 4H-SiC

We demonstrate the fabrication and characterization of epitaxial W
₂
C Schottky contacts into 4H-SiC via sputtering deposition of ultra-thin W followed by thermal annealing. The alloying reaction occurs below 600 °C, yielding a stable layer up to 1200 °C. The epitaxial layer is hexagonal, unexpectedly forming W
₂
C phase even at the lowest annealing temperature, which is predicted to occur at 1500 °C in bulk systems. Schottky contacts based on epitaxial W
₂
C films exhibit smoother interface morphology, higher thermal stability, lower turn-ON voltage and about ~50% reduction in Schottky-contact resistance compared with thick Ti Schottky contacts.