LASER-ASSISTED REACTIVITY OF TRIETHYLGALLIUM OR TRIMETHYLGALLIUM WITHAMMONIA IN CONSTRAINED PULSED NOZZLE EXPANSIONS

The results of laser-assisted reactivity in constrained gas expansions involving either triethylgallium (TEGa) or trimethylgallium (TMGa) wi th ammonia are reported. NH3 (or ND3) along with TEGa or TMGa are intr oduced into a high vacuum chamber through a customized dual-source pul sed nozzle assembly. Excimer laser output (193 or 248 nm) is focused i nto the mixing and reaction region of the nozzle source, and a quadrup ole mass spectrometer interrogates the photolyzed expansion. During ga s mixing and expansion into the vacuum, the adduct signals from TMGa:N H3 or TEGa:NH3 are observed when the nozzle assembly is cooled. Laser irradiation of the gas mixtures results in the formation of new adduct s, TMGa:NH2 or TEGa:NH2, and diverse, higher mass GaN-containing speci es. Power and wavelength dependence studies are used to reveal the pho tolytic origins of individual mass spectral features, and the influenc e of sample pressure on cluster formation processes is also examined.