(a) The electronic structure of the clean surface calculated using a surface unit cell with six layers in the vicinity of the Fermi level (indicated by the dashed horizontal line). The occupied ( and unoccupied bands of electronic surface states are indicated by the double-headed vertical arrows. (b) Schematic of the irreducible symmetry element of the surface Brillouin zone.
The surface electronic structure of the (a) HH1 and (b) HH2 Ge–Ge–H configurations calculated using a surface unit cell with six Ge layers in the vicinity of the Fermi level (indicated by the dashed horizontal line). The occupied and unoccupied bands of electronic surface states are indicated by the double-headed vertical arrows. The stars, empty circles, and filled squares indicate the surface states intrinsic to the Ge(001) substrate that are significantly affected by the chemisorption of a H atom onto one of the Ge–Ge dimers. [(c)–(f)] ILDOS plots for the HH1 and HH2 Ge–Ge–H configurations for the integration range of [(c) and (e)] and [(d) and (f)] for the isosurface value . To the right of the ILDOS plots are schematics of the HH1 [(c) and (d)] and HH2 [(e) and (f)] Ge–Ge–H hemihydride configurations. The large shaded circles indicate a Ge up atom and the small shaded circles denote the Ge down atoms. The hydrogen atom of the Ge–Ge–H hemihydride is represented by the small filled circle.
Surface electronic bandstructures calculated using a surface unit cell with six Ge layers for the [(a) and (b)] and [(c) and (d)] charged HH1 and HH2 configurations in the vicinity of (indicated by the dashed line). The hemihydride Ge atom dangling bond states are indicated by the filled and open circles, and the stars. The filled squares denote the surface states partially occupied by the delocalized, unpaired electron. Below the band structures are shown the schematics of the Ge–Ge–H hemihydride. The filled circles represent the electrons of the dangling bond.
ILDOS plots for the HH1 configuration (top row) and HH2 configuration (bottom row) for an integration range of . The left panels are for the neutral systems, the middle panels for one extra electron , and the right panels for the systems. The isosurface value is .
Filled-state STM images of a single Ge–Ge–H hemihydride on the Ge(001) surface at sample biases of (a) , (b) , (c) , and (d) . All images were acquired at tunneling current and are . The hemihydride is in the center of each image. The arrows indicate the position of an antiphase boundary that separates domains of periodicity.
Hemihydride buckling angles (in degrees) and bond lengths (in angstroms, given in brackets) calculated for the HH1 and HH2 configurations with zero, one and two additional electrons in the surface unit cell. A negative buckling angle indicates that the H-bonded Ge atom has become the down atom.
Article metrics loading...
Full text loading...