GaN fundamentals: 2DEG, crystal structure, and figure of merit

Gallium nitride (GaN) power devices are redefining the limits of switching converters by combining wide bandgap physics with lateral HEMT structures optimized for fast, low-loss operation. This article describes GaN as the natural successor to silicon MOSFETs in the 100–650 V class, showing how material figures of merit directly translate into lower on-resistance, higher switching frequency, and much higher power density at competitive cost.

Silicon power MOSFETs have driven the evolution of switch-mode power conversion since the late 1970s, replacing bipolar transistors, thanks to majority-carrier operation, ruggedness, and ease of drive. For decades, continuous structural improvements—cell pitch, trench, and superjunction—pushed R_DS(on) down while keeping breakdown capability and manufacturability. However, silicon is now essentially at its theoretical limit for unipolar devices in the 100–600 V range.

EDN
March 2026

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