Switches based on the wide band-gap semiconductors SiC (silicon carbide) and GaN (gallium nitride) have been gaining market share on their conventional silicon counterparts over the last decade or so because they deliver lower total losses at higher switching frequencies and power levels, all at an increasingly competitive price. SiC MOSFETs are far more popular than GaN (MOS)FETs, however, and the parenthetical aside, “(MOS)FETs,” is the first clue why: GaN switches can be constructed in numerous ways, with differing behaviors between them.

GaN does have its advantages, and in some applications, it is no hyperbole to call it a game-changer.

In contrast, SiC MOSFETs behave more or less the same as their conventional Si counterparts, and often come in the same standardized packages, so it’s entirely possible to get decent-enough results by merely substituting SiC for Si in an existing design (though getting optimal results will take some effort, so don’t be too lazy!).

SiC also has a much higher thermal conductivity and can operate at much higher junction temperatures than either GaN or Si—two advantages which are especially attractive in EV/hybrid applications. In an article that is ostensibly about GaN, this is sounding more like a sales pitch for SiC, but GaN does have its advantages, and in some applications, it is no hyperbole to call it a game-changer.

The goal behind the development of wide band-gap semiconductors is, somewhat paradoxically, to get them as close as possible to being an insulator without actually becoming one, because this reduces the physical size of the die for a given voltage and current rating.

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