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

Article abstract of DOI:10.1016/0039-6028(94)91293-9

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 meV 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 Si₃ N₄ and group-III nitrides at low temperatures is suggested.