Definition
Gallium Nitride (GaN) is a wide-bandgap semiconductor increasingly used in the power transistors of high-density switching supplies. With a bandgap of roughly 3.4eV and very high electron mobility, GaN devices, built as lateral high-electron-mobility transistors (HEMTs), sustain higher voltages and switch far faster than traditional silicon MOSFETs. For power-supply designers, that speed translates directly into smaller, cooler, more efficient converters.
Why GaN matters for power density
Switching loss is one of the biggest efficiency penalties in a switch-mode supply. Because a GaN HEMT turns on and off in nanoseconds with low gate charge and very low on-resistance, it bleeds far less energy on every switching cycle. That lets the converter run at much higher frequency, which shrinks the bulky magnetics and capacitors. The result is the kind of compact, high-wattage supply that AI data-center hardware and dense mining deployments increasingly rely on.
Where you see it
GaN first appeared in laptop chargers and is now common in server and high-end PSUs, especially in totem-pole PFC front ends where its fast, clean switching enables 99%-plus stage efficiency. The trade-offs are cost and gate-drive sensitivity: GaN switches so fast that layout parasitics and driver timing matter far more than with rugged silicon parts.
GaN is one of two wide-bandgap families reshaping power electronics; the other is covered in our silicon carbide (SiC) entry. Its speed advantage is what makes higher switching frequency practical.
In Simple Terms
Gallium Nitride (GaN) is a wide-bandgap semiconductor increasingly used in the power transistors of high-density switching supplies. With a bandgap of roughly 3.4eV and very…