Homo-epitaxial growth of rutile TiO2 film on step and terrace structured substrate

The atomically finished rutile TiO2 (1 0 1) substrate was obtained by an appropriate surface cleaning and subsequent annealing of commercially available single crystals. The morphology, composition and crystallinity of the ultrasmooth surface were confirmed by an atomic force microscope (AFM), an X-ray photoelectron spectroscopy (XPS) and a reflection-highenergy- electron diffraction (RHEED), respectively. The optimum process for obtaining the ultrasmooth surface was found to be the annealing at the temperature of 700 8C for 1 h in air after the ultrasonic cleaning immersing in organic solvents and subsequent 20% HF water solution. Furthermore, the homo-epitaxial growth on the ultrasmooth substrate was performed and compared with the hetero-epitaxial growth of TiO2 film on a stepped a-Al2O3 (1 0 1 2) substrate.