Formation and Properties of Schottky Diodes on 4H-SiC after High Temperature Annealing with Graphite Encapsulation
The impact of high temperature annealing using graphite encapsulation (formed by baking photoresist) on the electrical properties of Ni Schottky diodes formed on the annealed surfaces is studied. The surface morphology is also characterized by atomic force microscopy (AFM). Annealing for 10 minutes at temperatures up to 1800 °C with graphite encapsulation actually reduces the high-current ideality factor of the diodes while raising the current-voltage barrier height (linearly extrapolated to unity ideality factor) from 1.453 V to 1.67-1.73 V. Excess leakage current occurs only in a subset of diodes, which are believed to be affected by extended defects. The AFM images show no significant surface roughening, and the graphite can be removed after processing. This encapsulation method is found to be highly effective in preserving the electronic properties of the surface during high temperature annealing.
Robert P. Devaty, David J. Larkin and Stephen E. Saddow
Y. Wang et al., "Formation and Properties of Schottky Diodes on 4H-SiC after High Temperature Annealing with Graphite Encapsulation", Materials Science Forum, Vols. 527-529, pp. 915-918, 2006