GaNs

GaNs refers to gallium nitride and related wide-bandgap semiconductors used in a variety of electronic and optoelectronic applications. The principal compound, GaN, has a direct bandgap of about 3.4 eV at room temperature, placing its emission in the near-ultraviolet to blue region. GaN also features a high breakdown electric field, on the order of 3 MV/cm, and a thermal conductivity around 130 W/m·K, with relatively high electron mobility when lightly doped. These properties enable devices that operate at high voltages, high temperatures, and high frequencies, making GaN a core material for power electronics and high-frequency systems, as well as for light emission.

Growth and substrates: GaN films are typically grown by epitaxial techniques such as metal-organic chemical vapor deposition (MOCVD) or hydride vapor phase epitaxy (HVPE). Because GaN is often grown on lattice-mismatched substrates, common choices include sapphire (Al2O3), silicon carbide (SiC), or bulk GaN substrates, with buffer layers used to reduce defect densities. Doping is straightforward for n-type regions (commonly silicon); p-type doping via magnesium is more challenging due to deep acceptor levels and compensation, though thermal treatment can activate Mg in many devices. Many GaN devices exploit AlGaN/GaN heterostructures to form a high-mobility two-dimensional electron gas for high-electron-mobility transistors (HEMTs).

Applications and impact: GaN-based LEDs enabled efficient blue and white light sources, while GaN laser diodes extend into blue/UV wavelengths. In power electronics, GaN HEMTs offer higher breakdown voltage, faster switching, and improved efficiency over silicon counterparts, supporting compact power supplies and chargers. GaN also supports ultraviolet photodetectors and high-frequency RF components that are in commercial use or development.

History: The development of bright GaN blue LEDs in the 1990s, culminating in significant demonstrations and commercialization, led to the 2014 Nobel Prize in Physics for researchers Akasaki, Amano, and Nakamura, recognizing advances in GaN-based optoelectronics.