III-V group compound semiconductor formed by group-III and group-V elements. Alumium(Al),Gallium(Ga),Indium(In) are typical group-III elements while Nitrogen(N), Phosphorus(P), Arsenic (As) and Antimony (Sb) are belong to group-V elements.
GaN,AlN and InN compound which use group-V element Nitrogen are particularly called as Nitrogen compound.

Many of III-V compound semiconductors are directly transition semiconductors therefore can be used in emition elements like LED or LD.

Further,compound semiconductors have different bandgap compared with Silicon (Si) so they can also be used in light-receiving elements like photo diode.

Moreover,they are also widely used in electrical device such as power amplifier or switch,high-speed circit of mobile phone or wireless LAN which is active around our daily lilves.