Chemical and structural properties of ternary post-transition metal oxide thin films: InZnO, InGaO and GaZnO

• We investigated the chemical states of InGaO, GaZnO and InZnO thin films using XPS.
• The O 1s binding energy changed with the composition.
• We conclude that the charge transfer effect between the cations and O ions is significant.
• EXAFS study shows that the cation-oxygen coordination is roughly maintained.
• The charge transfer process via O-ions can influence the charge reconstruction in the films.

The chemical states of ternary post-transition metal oxide thin films of InGaO, GaZnO and InZnO were investigated using X-ray photoelectron spectroscopy. Detailed binding energy (BE) analyses revealed certain evolution in chemistry in the ternary oxides compared to the reference binary oxides of In2O3, ZnO, or Ga2O3. In particular, O 1s BEs were changed with the compositions, which suggests that the charge transfer (CT) between In3+/Ga3+/Zn2+ and O2− ions is significant. Results of extended X-ray absorption fine structure analyses further showed that the first shell coordination (cation–O bond) is roughly maintained even though the ternary oxide films were structurally disordered. This implies that the CT process via O2− ions can influence the charge reconstructions in the ternary oxide systems.