Valence and core level photoemission spectra of AlxGa1−xAs

A linear shift towards the top of the valence band with increasing Al-content was observed for all features in the valence band spectra of Al_xGa_1?xAs. The binding energies of the metallic core levels remained invariant, whereas those of As decreased with increasing Al concentration. The results are interpreted in terms of an increasing ionicity with Al content.