A cross-sectional scanning tunneling microscopy study of IrO2 rutile single crystals

Rutile iridium dioxide (IrO2) surfaces were studied by cross-sectional scanning tunneling microscopy (XSTM). Atomically flat surfaces prepared by in situ ultra high vacuum cleaving of crystalline platelets of thicknesses <50 μm were successfully demonstrated. In addition to (1 1 0) surface, several vicinal planes, e.g., (1 2 0), (1 3 0) and ∼(891¯), were also examined. The cleaved planes are close to bulk-terminated surfaces with predominant [0 0 1]-oriented bridge oxygen rows. Unlike TiO2, bright oxygen rows are imaged and oxygen defects appear as dim species. Our studies show that XSTM is a viable technique to study oxide surfaces that are otherwise difficult to prepare.