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

Abstract

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 φ B =1.05 eV and n=1.02 for Mo and φ B =1.2 eV and n=1.02 for W, respectively. The diodes showed an R on in the range of 1.8 up to 2.4 mΩ cm 2 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.