A high-resolution spectroscopy study on bidimensional ordered structures: the (1x1) and(1x2) phases of Bi/InAs(110)

The room-temperature growth of bismuth on the InAs(110) surface and the Bi( 1 x 1) and Bi-(1 x 2) ordered phases have been studied by means of high-res olution ultraviolet photoemission and high-resolution electron-energy-loss spectroscopy A modified Stransky-Krastanov growth mode at room temperature and the stability of the (1 x 2)-symmetry phase in the 480-580 K annealing temperature range are deduced by quantitative analysis of the core-level da ta and Auger spectra. A Bi 5d and In 4d core-level analysis is presented, a nd discussed according to a recently proposed model for the (1 x 2) overlay er reconstruction. The formation of Bi-derived electronic states has been f ollowed during the growth of the (1 x 1)-symmetry phase, showing a semicond ucting behaviour at the monolayer coverage, with a well-defined gap stare a t 0.39 eV binding energy related to the Bi p-like dangling bonds. The (1 x 2)-Bi phase is metallic, as indicated by the well-defined Fermi edge and by the metallic-like quasi-elastic peak tail in the energy-loss spectra. The metallicity and the electronic structure of the (1 x 2)-Bi phase are discus sed in relation to the available geometric structure.