Atomic topography and self-assembly of one-dimensional potassium chains on the InAs(110) surface

One-dimensional (1D) potassium chains, obtained on the InAs(110) surface, are studied by scanning tunneling microscopy (STM). The (2xn) symmetry in the low energy electron diffraction pattern, becoming a c(2x6) structure at the completion of the first layer, is explained by the various spacing D between alkali chains in the [001] direction. The distribution of D as a function of the chain density suggests the presence of a repulsive interaction among the chains, which drives the self-assembling of the 1D structures. The origin of the interaction is discussed in comparison with the model proposed for the Cs/InAs(110) interface, showing the general validity of the model for this class of chain structures. The atomic structure of an isolated chain is investigated by high-resolution STM images, revealing the asymmetry in the charge density induced by K adatoms and a modification of the As-related charge density of the topmost substrate layer.