Ni-Al-Ti ohmic contacts with preserved form factor and few 10^{- 4} ?cm² specific resistance on 0.1-1 ?cm p-type 4H-SiC

This study shows that a thin Ni film on Al/Ti/4H-SiC metal pads allows to preserve the pad form factor during a 1000 °C/2 min treatment, provided that the Al and Ti film thicknesses are sufficiently thin. Moreover, by reducing the Al to Ti thickness ratio, droplet formation in the contact area is avoided and a mirror-like appearance is obtained. This optimal contact morphology corresponds to a specific contact resistance of few 10 ?cm at room temperature on p-type 4HSiC with resistivity in the range 0.1-1 ?cm.