Electronic and structural properties of the surfaces and interfaces of indium oxide

Indium sesquioxide is a transparent conducting oxide material widely used in solar cell and solid‐state lighting devices. Following our recent successes in modeling the electronic and defect properties of $In2O3,$ we report an investigation of the surface physics of this material. In the ground‐state bixbyite phase, the surface energies follow the order $(100)>(110)>(111),$ with the charge neutral (111) termination being the lowest energy cleavage plane; the same ordering preferences have been established for materials adopting the parent fluorite $(AB2)$ structure. Our first‐principles predictions, based on density functional theory, are confirmed through collaboration with the group of Russell Egdell at Oxford University, who grew epitaxial $In2O3$ single crystals on lattice matched (100),(110) and (111) Y‐stabilized zirconia substrates, and observed that (111) facets spontaneously form on other low index terminations. Furthermore, we have performed work function analysis of the low index $In2O3$ surfaces using a hybrid density functional, which is found to be in very good agreement with recent experiments.