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 degreesC, 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 phi (B) = 1.05 eV and n = 1.02 for Mo and phi (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 m Omega 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. (C) 2001 Elsevier Science B.V. All rights reserved.