Experimental studies of an In/Pb binary surface alloy on Ge(111)

In this study, we present a binary In/Pb surface alloy on Ge(111) formed by evaporating0.85 monolayer (ML) of In on the Pb/Ge(111) surface with 1.33 ML of Pb. A welldefined3×3 periodicity is formed after annealing at a temperature of ≈200 °C, as verified by bothlow energy electron diffraction (LEED) and scanning tunneling microscopy (STM). OverviewSTM images, obtained at 50 K, show a clear 3×3 periodicity. Detailed STM images reveal thatthe protrusions consist of atomic sized features with a local hexagonal arrangement. Each 3×3unit cell contains nine such features indicating a structure with 9 atoms per 3×3 cell. Based onangle resolved photoelectron spectroscopy (ARPES) data, we have identified five surface bandswithin the bulk band gap. Four of them cross the Fermi level leading to a metallic character of thesurface. The dispersions of these bands have been mapped in detail along the high symmetrydirections of the 3×3 surface Brillouin zone. Fermi contours, mapped in 2D k-space, showinteresting features. In particular, the occurrence of two differently rotated hexagon like contoursis discussed.Funding agencies:Technical support from Dr. Johan Adell and Dr. T. Balasubramanian at MAX-lab is gratefully acknowledged.Vid tiden för disputation förelåg publikationen som manuskript