A method is disclosed for growing a nitrogen-containing III-V alloy semiconductor on a semiconductor substrate such as GaAs, which is formed by MOCVD method using nitrogen containing organic compounds having relatively low dissociation temperatures. The alloy semiconductor has a high nitrogen content which exceeds the contents previously achieved, and has a high photoluminescence intensity.There are also disclosed fabrications of semiconductor devices comprising the alloy semiconductors, such as heterostructure and homo-junction light emitting devices.