Chemisorption site geometry and interface electronic structure of Ga and Al on GaAs(110)

Valence‐band photoemission spectra taken as a function of overlayer coverage during the formation of Ga–GaAs(110) and Al–GaAs(110) interfaces are analyzed. Possible chemisorption site geometries of Ga on GaAs(110) are studied through total energy calculations and the surface electronic structure for Ga (or Al) in an optimal twofold configuration as well as for the ideal onefold coordinated position is obtained. The calculations show that the interface formation results in a change in the relaxation of the GaAs surface from its vacuum interface configuration. This interfacial relaxation at the initial stage of metal–semiconductor interface formation pulls unoccupied surface states into the gap and pins the Fermi level.