Barrier non-uniformity of annealed Ni/4H-SiC Schottky contacts with temperature

The barrier non-uniformities of Schottky diodes with Ni/4H-SiC contacts, post-metallization annealed at 800°C, are investigated at temperatures up to 450°C. Simulations and measurements are used to determine barrier height and ideality factor variations when the contact is comprised of two different metal regions (low-barrier patches in the high-barrier contact area) and affected by interface states. Measured devices show almost ideal forward characteristics after 225°C, but inconsistencies in barrier height value still indicate surface inhomogeneity. The maximum operating temperature of these devices is discussed.