Valence-band discontinuity at the interface

Abstract

The growth of fullerene films on surfaces and the formation of the interface was studied using low-energy electron diffraction, Auger electron spectroscopy and x-ray as well as ultraviolet photoemission spectroscopy. The initial growth of proceeds layer-by-layer. No chemical reactions or interdiffusion were observed. The deposition does not change the binding energies of Si(2p) and C(1s) electrons. Therefore, the band bending of the clean surface remains the same, irrespective of the coverage. The photoemission measurements yield a valence-band discontinuity of eV at the interface. The band line-up at semiconductor interfaces is explained by the adjustment of the branch points in the continuum of the interface-induced gap states. Our experimentally observed valence-band offset agrees well with the theoretical predictions if the branch point of is assumed at midgap position.