The 308 nm laser photodissociation of HN₃ adsorbed on Si(111)-7 × 7

The photodissociation of HN₃ adsorbed on Si(111)-7 × 7 at 308 nm was investigated using HREELS and XPS. Species such as NH_x, N₂, and N₃, were identified on the surface with comparable concentrations after the irradiation with 1 × 10²⁰ photons of a 10 L HN₃ dosed Si(111) surface. The N₃ species showed two stretching modes at 178 and 255 meV, while that of the N₂ appeared at 206 me V in HREELS. The formation of these products was also corroborated by the corresponding XPS results. Further laser irradiation caused the dissociation and partial desorption of the adsorbates with NH_x left on the surface. Annealing the post-irradiated sample to 500 and 800 K resulted in the breaking of the NH bond and the desorption of the H-species, while the atomic N remained on the surface forming silicon nitride. The possibility of using HN₃ for laser-induced chemical vapor deposition of Si₃N₄ and group-III nitrides at low temperatures is suggested.