AlGaNGaN

AlGaN refers to the ternary III-nitride alloy formed by aluminum nitride and gallium nitride, with the chemical composition AlxGa(1−x)N. By varying x from 0 to 1, the material's bandgap can be tuned from about 3.4 eV for GaN to about 6.2 eV for AlN, enabling devices that operate across the visible to deep ultraviolet range. AlGaN is commonly used in combination with GaN in heterostructures and is a key component in UV optoelectronics and high-electron-mobility devices.

The alloy crystallizes in the wurtzite structure and exhibits strong spontaneous and piezoelectric polarization. This polarization leads to internal electric fields that influence optical transitions and, in AlGaN/GaN heterostructures, can create a high-density two-dimensional electron gas at the interface, a feature exploited in high-electron-m mobility transistors (HEMTs). The lattice constants of AlGaN vary with composition, and increasing aluminum content introduces greater lattice mismatch with common substrates, contributing to strain and defect formation.

Growth and synthesis typically employ metal-organic chemical vapor deposition (MOCVD) or hydride vapor phase epitaxy (HVPE). Common substrates include sapphire (Al2O3), silicon carbide (SiC), and bulk GaN. Doping is possible with silicon for n-type and magnesium for p-type, though achieving reliable p-type conductivity becomes more difficult as Al content rises.

Applications include deep ultraviolet light-emitting diodes and laser diodes, UV photodetectors, and AlGaN/GaN HEMTs for RF and power electronics. Ongoing research addresses material quality at high Al content, control of polarization effects, defect reduction, and improved p-type doping to expand device性能 and reliability.