Evidence for surface dipole modifications in In₂O₃-based transparent conductors

Surface dipole modifications were identified for contamination-free In₂O₃-based transparent conducting oxides by ultraviolet photoelectron spectroscopy on both thin film and bulk ceramic specimens. In particular, heating in air was found to result in an increase in ionization potential and work function. The formation of surface dipoles may be related to the unique structure (crystal, defect) of bixbyite-based materials. These findings have important ramifications for the tuning of work functions in In₂O₃-based transparent conductors.