Mechanism of the photochemically induced reaction between Ga(CH3)3 and HN3 and the deposition of GaN films

Gaseous HN3 reacts with surface-bound Ga(CH3)x species slowly at 300 K to produce thin films containing azide-substituted gallium compounds. When mixtures of HN3 and Ga(CH3)3 over the surface are irradiated at 253.7 nm, the reaction is dramatically accelerated, and films containing GaN and complexed N2 are produced. Heating of these films to 400 K drives off the N2 leaving GaN. The mechanism of the reaction is thought to involve photodissociation of HN3 to produce excited NH(a1Δ) and N2, followed by insertion of the NH(a1Δ) into the Ga–C bond of surface-bound Ga(CH3)x molecules. The insertion product eliminates CH4 to leave GaN.