We used photoemission spectroscopy with synchrotron radiation to investigate the formation and the microscopic properties of interfaces between semiconducting substrates and Si overlayers deposited by electron bombardment. The main goal of the experiment was to measure the valence band discontinuity in these systems and test the limits of the discontinuity transitivity rule predicted by all ‘‘linear’’ models. This rule could be tested by combining our present data on Si overlayers and previous data on Ge overlayers on Si, GaAs, and CdS. We found that the rule is valid for the above interfaces only within an accuracy of a few tenths of an electron volt. Our results are in agreement with recent evidence that the Harrison LCAO approach, one of the ‘‘linear’’ models, predicts the valence band discontinuities with an accuracy of the order of ∼0.25 eV.