What are SiC Schottky barrier diodes?Advantages of using SiC-SBDs

We have compared the characteristics of SiC-SBDs with those of Si diodes, and have described products that are currently available. This time, while summarizing our discussion thus far, we would like to consider the advantages of SiC-SBDs.

Characteristics of SiC-SBDs, Si SBDs and Si PNDs

In a SiC-SBD, a metal junction with the SiC semiconductor (a Schottky junction) is formed to obtain a Schottky barrier. The structure is essentially the same as that of a Si Schottky barrier diode, and only electrons move to cause current to flow. In contrast, a Si-PND has a structure based on a junction of P-type silicon and N-type silicon, and current flows due to both electrons and holes.

Both SiC-SBDs and Si SBDs feature fast operation, but SiC-SBDs achieve high rated voltages together with fast operation. 200 V is the upper limit to the Si-SBD rated voltages, but SiC has a dielectric breakdown field some ten times higher than that of silicon, and so SiC products with a rated voltage of 1200 V are being mass produced, and products with a voltage of 1700 V are in development.

Si-PNDs have a reduced resistance due to accumulation of minority carrier holes in the n layer, and so can simultaneously realize low resistance and high voltages far beyond those of Si-SBDs, but turn-off speeds are slow.

Among Si-PNDs, FRDs boast faster operation, but even so the trr characteristic is inferior to that of SBDs.

The diagram on the right indicates the rated voltage ranges for Si-SBDs, Si-PNDs/FRDs, and SiC-SBDs. SiC-SBDs extend over a considerable part of the voltage range of Si- PNDs/FRDs, and so improvement on the trr of Si-PNDs/FRDs is possible in this region.

trr Values of SiC-SBDs

In comparisons with Si-FRDs, it was explained that Si-SBDs have excellent trr characteristics, and exhibit almost no dependence on temperature or current.