THE CLEAN AND HYDROGENATED GE(113) SURFACE STUDIED BY ANGLE-RESOLVED PHOTO-ELECTRON SPECTROSCOPY

Angle-resolved UV photo-electron spectroscopy (ARUPS) was applied to t he valence bands of the Ge(113) surface. Using the known Ge bulk band structure, the position of the valence-band maximum (VBM) relative to the Fermi level was measured. Electronic surface resonances were ident ified on the clean (3 x 2)-reconstructed surface. The dispersion of th e surface resonances was studied in the main symmetry directions. It r eflects the periodicity of the surface only along the [1 $($) over bar $$ 10] azimuth but not along [33 $$($) over bar 2]. Adsorption of hydr ogen leads to a change of the surface reconstruction to (3 x 1)-H conn ected with a quenching of the surface resonances found on the clean su rface. Further hydrogenation changes the surface into a (1 x 1)-H stru cture and a dispersing H-induced state appears at -5.5 eV relative to the VBM.