Gap-state formation in two-dimensional ordered Bi layers on InAs(110)

The spectral density at the Fermi energy and the formation of adlayer-induced electronic states is studied by means of high energy resolution ultraviolet photoemission spectroscopy. A highly ordered (1x1)-Bi monolayer deposited on InAs(110) induces a well-resolved, occupied electronic state in the InAs surface gap, attributed to p-like dangling bonds at the Bi atomic chains. Appropriate annealing of a Bi multilayer produces a (1x2)-symmetry stable phase. Evolution of the spectral density close to the Fermi edge brings to light the metallicity of the (1 x 2)-Bi layer induced by Bi-Bi bonding in the atomic chains.