Tungsten, nickel, and molybdenum Schottky diodes with different edge termination

In this paper, we report on the fabrication and electrical characterization of Mo-, Ni-, and W-Schottky diodes on 4H–SiC. Due to their fast switching behavior and the capability to block high voltages even at temperatures above 200 °C, SiC-Schottky diodes are a promising device for high power and high temperature applications. Because of being compatible to a standard silicon process technology and their thermal stability, the refractory metals W, Ni, and Mo seem to be a well-suited choice for fabricating ohmic and Schottky contacts. The electrical behavior of Mo-, Ni-, and W-Schottky diodes on 4H–SiC with different areas and with different edge termination techniques was compared. The diodes showed a barrier height and an ideality factor of φB=1.05 eV and n=1.02 for Mo and φB=1.2 eV and n=1.02 for W, respectively. The diodes showed an Ron in the range of 1.8 up to 2.4 mΩ cm2 at 1.5 V. For edge termination, high resistivity guard rings manufactured by aluminum and carbon ion-implanted areas were used. This approach led to transient phenomena in the I–V characteristics, which was not found in the case of doped guard rings.