Aluminium gallium arsenide

 ( Arsenides ) 

Aluminium gallium arsenide (also gallium aluminium arsenide) (Aluminium_xgallium_1−xarsenic) is a semiconductor material with very nearly the same lattice constant as Gallium arsenide, but a larger bandgap. The x in the formula above is a number between 0 and 1 - this indicates an arbitrary alloy between Gallium arsenide and AlAs.

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

The bandgap varies between 1.42 electron volt (GaAs) and 2.16 eV (AlAs). For x < 0.4, the direct bandgap.

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 used in , , and substrate-transferred crystalline coatings.

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 (700–1100 nm) double-hetero-structure .

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Safety and toxicity aspects The toxicology of AlGaAs has not been fully investigated. The dust is an irritant to skin, eyes and lungs. The environment, health and safety aspects of aluminium gallium arsenide sources (such as trimethylgallium and arsine) and industrial hygiene monitoring studies of standard MOVPE sources have been reported recently in a review.

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