Gallium Nitride (GaN): The Wide-Bandgap Semiconductor Behind Blue LEDs and Fast Chargers

Gallium nitride (GaN) is a compound of gallium and nitrogen and a leading "third-generation" wide-bandgap semiconductor. It has a direct bandgap of about 3.4 eV at room temperature (versus silicon's ~1.1 eV), a wurtzite crystal structure, electron mobility around 1500 cm2/V/s, and a melting point above 1600 C. GaN's first transformative use was in optoelectronics: efficient blue LEDs and violet laser diodes (the latter used in Blu-ray drives) became possible in the 1990s, work later recognized with the 2014 Nobel Prize in Physics. The same wide bandgap that produces blue/violet light also enables high-power, high-temperature, high-frequency electronics. In power and RF applications, GaN is usually built as a high-electron-mobility transistor (HEMT), which exploits a fast two-dimensional electron gas at a heterojunction. GaN HEMTs operate at higher temperatures (~400 C versus silicon's ~150 C) and far higher frequencies than silicon, and switch much faster with lower losses. This makes GaN the material behind compact USB-C "GaN chargers," efficient power supplies, EV onboard chargers, and AESA radar amplifiers. Compared with Silicon Carbide (SiC): The Wide-Bandgap Semiconductor for Power Electronics, GaN generally wins at high switching frequency and lower-to-medium power, while SiC wins at the highest voltages and currents. Both are commercialized today, unlike the research-stage Graphene: The Single-Atom-Thick Carbon Sheet With No Bandgap and Transition Metal Dichalcogenides (TMDs): Atomically Thin 2D Semiconductors. See No Single Successor to Silicon: The Heterogeneous Future of Chip Materials for the broader landscape.