THE 308 NM LASER PHOTODISSOCIATION OF HN3 ADSORBED ON SI(111)-7X7

The photodissociation of HN3 adsorbed on Si(111)-7 X 7 at 308 nm was i nvestigated using HREELS and XPS. Species such as NHx, N-2, and N-3, w ere identified on the surface with comparable concentrations after the irradiation with 1 x 10(20) photons of a 10 L HN3 dosed Si(111) surfa ce. The N-3 species showed two stretching modes at 178 and 255 meV, wh ile that of the N-2 appeared at 206 meV in HREELS, The formation of th ese products was also corroborated by the corresponding XPS results. F urther laser irradiation caused the dissociation and partial desorptio n of the adsorbates with NHx left on the surface. Annealing the post-i rradiated sample to 500 and 800 K resulted in the breaking of the NH b ond and the desorption of the H-species, while the atomic N remained o n the surface forming silicon nitride. The possibility of using HN3 fo r laser-induced chemical vapor deposition of Si3N4 and group-III nitri des at low temperatures is suggested.