ZnO 2p peaks for pure ZnO are observed at binding energies of

1021.2 and 1044.2 eV, respectively. Binding energies for the Al-doped ZnO samples increase by 0.5 eV compared with the pure ZnO sample. What are the possible reasons for understanding purpose. If compared separately with undoped ZnO and doped with Al samples, the binding energy decreases to lower values.

Does any body know how to explain this effect in AZO and ZnO thin films.