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 ~131!-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 ~132!-symmetry stable phase. Evolution of the spectral density close to the Fermi edge brings to light the metallicity of the ~132!-Bi layer induced by Bi--Bi bonding in the atomic chains.