Geometric and electronic properties of Cs structures on III-V (110) surfaces: From 1D and 2D insulators to 3D metals

We report the structural and electronic properties of Cs adsorbed on room-temperature GaAs and InSb (110) surfaces as observed with scanning tunneling microscopy. Cs initially forms long one-dimensional (1D) zigzag chains on both surfaces. Additional Cs adsorption on GaAs(110) results in the formation of a 2D overlayer consisting of five-atom Cs polygons arranged in c(4×4) superlattice. The tunneling gap measured over these insulating structures narrows with the transition from 1D to 2D, with metallic characteristics observed following saturation with a second Cs overlayer.