Potassium assembled on the InAs(1 1 0) surface: from nanowires to two-dimensional layers

Long-range ordered chain structures can be assembled by depositing potassium on the clean InAs(1 1 0) surface held at 420 K. Potassium wires are formed along the [1 1̄ 0] direction at coverage as low as Θ=0.02, as observed by scanning tunneling microscopy. The chain density increases by further K adsorption and a c(2×6) symmetry can be detected by LEED at the completion of the first ordered layer. Further deposition induces a second ordered potassium overlayer on top of the alkali wires with a c(4×4) symmetry. The regularly-shaped unit blocks are constituted by four potassium adatoms aligned along the underlying row structure. Scanning tunneling spectroscopy (STS) does not detect an electronic density of states at the fermi level indicating the insulating character of the one-dimensional (1D) and two-dimensional (2D) systems.