Heterojunctions between Si(111):H faces and molecular beam epitaxy grown thin films were investigated. The interface formation was studied by means of photoelectron spectroscopy and low energy electron diffraction. Initial sulfur exposure of the Si substrate at 750 K leads to a surface dipole of (0.61±0.10) eV. Upon subsequent deposition, an interface dipole of (1.0±0.2) eV is observed. The valence band offsets between Si and films of different [Cu]/[In] ratios were determined and an average valence band offset of (0.08±0.15) eV is obtained. Comparison with model considerations points out that the experimental values of the valence band offset are consistent with the observed interface dipole.
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