SiC and GaN devices - wide bandgap is not all the same

Abstract

Silicon carbide (SiC)-diodes have been commercially available since 2001 and various SiC-switches have been launched recently. Parallelly, gallium nitride (GaN) is moving into power electronics and the first low-voltage devices are already on the market. Currently, it seems that GaN-transistors are ideal for high frequency ICs up to 1kV (maybe 2kV) and maximum a few 10A. SiC transistors are better suited for discrete devices or modules blocking 1kV and above and virtually no limit in the current but in that range they will face strong competition from the silicon insulated gate bipolar transistors (IGBTs). SiC and GaN Schottky-diodes would offer a similar performance, hence here it becomes apparent that material cost and quality will finally decide the commercial success of wide bandgap devices. Bulk GaN is still prohibitively expensive, whereas GaN on silicon would offer an unrivalled cost advantage. Devices made from the latter could be even cheaper than silicon devices. However, packaging is already a limiting factor for silicon devices even more so in exploiting the advantage of wide bandgap materials with respect to switching speed and high temperature operation. After all, reliability is a must for any device no matter which material it is made of. © The Institution of Engineering and Technology 2014.