Relative core level deformation potentials in strained layer heterojunctions

Accurate determination of the valence‐band discontinuity (ΔEv) at a pseudomorphic heterojunction interface from x‐ray photoemission spectroscopy (XPS) core level measurements requires knowledge of hydrostatic core level to valence‐band centroid binding energy shifts. These shifts can be calculated theoretically. Experiments are reported which measure relative core level deformation potentials in strained layer heterojunctions to test the accuracy of the calculated binding energy shifts. The measurements and calculations are not in good agreement; caution is suggested in deriving ΔEv at pseudomorphic heterojunction interfaces by combining calculated deformation potentials with XPS data until this discrepancy is resolved.