Atomic force microscopic observation of SrTiO sub(3) polar surface

The structure change of SrTiO sub(3) (111) polar surface was studied as a function of atmosphere. Atomic force microscopy (AFM) and coaxitial impact-collision ion-scattering spectroscopy (CAICISS) were used to study the surface structure of the (111) polar surfaces of SrTiO sub(3) single crystals. From the result of AFM observation, the polar surfaces annealed in oxygen gas had a trench structure, and that annealed in argon gas formed large triangular terraces. The surface annealed in air, i.e. in intermediate oxygen partial pressure, consisted of complicated self-similar triangles with different sizes, forming a fractal shape called Sierpinski's gasket. The time of flight spectra of CAICISS suggested that a Ti super(4+) plane was more stable than a SrO super(4) sub(3) super(-) plane on the substrate surface annealed in oxygen gas, and the Ti super(4+) and SrO super(4) sub(3) super(-) planes almost equally existed on the substrate surface annealed in argon gas. Molecular dynamic calculations at constant temperature and pressure were applied for various SrTiO sub(3) (111) polar surfaces.