CORE-LEVEL PHOTOEMISSION-STUDY OF HYDROGENATED GAAS(100) SURFACES

The interaction of atomic hydrogen with GaAs(100) surfaces has been st udied at room temperature by means of photoelectron spectroscopy using synchrotron radiation. Atomic hydrogen produces drastic changes in th e line shape of the As3d and Ga3d core levels and changes in the As/Ga intensity ratio. A least-squares fit routine for line shape analysis enables the identification of different contributions. They show the b reaking of Ga-dimers in the low exposure region (<10(2) L) and the for mation of Ga- and As-hydrides between 10(2) L and 10(4) L. In addition the build up of metallic Ga-droplets after higher exposures is shown. The intensity ratio of As3d to Ga3d indicates an As-enrichment due to Ga-hydride desorption and Ga-droplet formation.