Correlation between height selection and electronic structure of the uniform height Pb/Si(111) islands

Uniform-height islands, with preferred heights differing by bilayer height increments, can be grown on Pb/Si(111) at low temperatures most likely as a result of quantum size effects. With scanning-tunneling-microscope spectroscopy we have determined how the electronic structure of individual islands is related to their stability. Differences between preferred vs nonpreferred island heights are seen at the position of the Fermi level with respect to the highest occupied band and lowest unoccupied band. This difference is supported from oscillations of the measured apparent barrier Delta(lnI)/Deltaz with island height.