Aluminium gallium arsenide

Aluminium gallium arsenide (also Aluminum gallium arsenide) (Al_xGa_1-xAs) is a semiconductor with the 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).

The formula AlGaAs should be considered an abbreviated form of the above, rather than any particular ratio.