After years of R&D in the lab, compound semiconductor materials like silicon carbide (SiC) and gallium nitride (GaN) used for ICs are taking a bigger role in handling electrical power. These wide-bandgap (WBG) devices are ready to carve out a niche in applications that demand the ability to work at high voltages and temperatures while demonstrating high efficiency. They’re poised to take over designs based on insulated-gate bipolar transistor (IGBT) technology.
One big factor to be overcome is a relatively higher price, which manufacturers are trying to tackle by using larger wafers. Another issue concerns instabilities in the threshold voltage level caused by a messy transition region between the pure SiC and the grown SiO2 that inhibits carrier mobility. Progress, however, is being made here as well.
Nevertheless, IGBT technology isn’t sitting back, with companies looking to make improvements. IGBTs can block high voltages with low on-state conduction losses and well-controlled switching times. But they’re limited by how fast they can switch while delivering low on-state conduction losses. This leads to a need for costly and large-size thermal-management methods and a limitation on power-conversion system efficiency.