GaseousHN3reacts with surface-boundGa(CH3)xspecies slowly at 300 K to produce thin films containing azide-substituted gallium compounds. When mixtures ofHN3andGa(CH3)3over the surface are irradiated at 253.7 nm, the reaction is dramatically accelerated, and films containing GaN and complexedN2are produced. Heating of these films to 400 K drives off theN2leaving GaN. The mechanism of the reaction is thought to involve photodissociation ofHN3to produce excitedNH(a1&Dgr;)andN2,followed by insertion of theNH(a1&Dgr;)into the Ga–C bond of surface-boundGa(CH3)xmolecules. The insertion product eliminatesCH4to leave GaN. ©1998 American Institute of Physics.