Wiktionary
n. (context inorganic compound English) A mixed arsenide of aluminium and gallium that is used as a semiconductor
Wikipedia
Aluminium gallium arsenide (also aluminum gallium arsenide) ( Al Ga As) is a semiconductor material with very nearly the same lattice constant as GaAs, but a larger bandgap. The x in the formula above is a number between 0 and 1 - this indicates an arbitrary alloy between GaAs and AlAs.
The bandgap varies between 1.42 eV (GaAs) and 2.16 eV (AlAs). For x < 0.4, the bandgap is direct. The refractive index is related with the bandgap via the Kramers–Kronig relations and varies between 2.9 (x = 1) and 3.5 (x = 0). This allows the construction of Bragg mirrors used in VCSELs and RCLEDs.
The formula AlGaAs should be considered an abbreviated form of the above, rather than any particular ratio.
Aluminium gallium arsenide is used as a barrier material in GaAs based heterostructure devices. The AlGaAs layer confines the electrons to a gallium arsenide region. An example of such a device is a quantum well infrared photodetector ( QWIP).
It is commonly used in GaAs-based red- and near- infra-red-emitting (700nm-1100nm) double-hetero-structure laser diodes.
Usage examples of "aluminium gallium arsenide".
These resonant tunnelling computer chips are constructed not of silicone, not even of the newest hyperfast conductive alloys, indium phosphide and aluminium gallium arsenide.
Laser transistors composed of atomic layers not of indium phosphide and aluminium gallium arsenide but of a monocrystalline diamond film were all well and good for high electron mobility (in fact, he was astounded that the Americans actually had perfected them) but, the Scoundrel knew, under the right circumstances they actually could work to his advantage.