Semiconductor material composed of elements from two or more different groups of the periodic table. They can be formed of elements from group III (e.g.: Al, Ga, In) and from group V (N, P, Ar, Sb). The range is quite broad because there can not just be binaries like GaAs, but also , ternary like GaInAs and quaternary (AlInGaP) alloys.
Compound semiconductors are particularly important for opto-electronic devices.