Abstract
We prepared SrTiO 3 (110) surfaces by reducing and sputtering in UHV at high temperatures of around 1000°C. The as-prepared samples were characterized using low energy electron diffraction (LEED), Auger electron spectroscopy and scanning tunneling microscopy (STM). LEED experiments revealed the existence of a variety of reconstructed surfaces of the type ( n × m). In some cases we attributed missing LEED spots to an incommensurability of the surface structure in the [11̄0] direction. These results were confirmed by STM measurements. STM images of the as-prepared SrTiO 3 (110) surfaces showed stripe-like surface structures running in the [11̄0] direction consisting of individual building blocks. These blocks were frequently found to be uncorrelated between adjacent stripes. SrTiO 3 (110) samples, only slightly annealed, yielded a different surface structure. The STM measurements revealed a micro-faceted surface. Our STM measurements allowed direct observation of the (1 × 1) surface periodicity of the SrTiO 3 (110) surface due to tunneling into empty states of Ti 2+ Ti 3+ sites at the surface. Our results suggest the necessity of special treatments of the SrTiO 3 (110) surfaces in order to get the smooth, homogeneous surfaces, imperative for growing high quality (110)- or (103) (013) - oriented RBa 2Cu 3O 7− δ thin films. Auger measurements showed that the surface concentration of strontium increases with respect to titanium with increasing annealing temperature. This behavior is different from other SrTiO 3 surfaces. The surface concentration of oxygen with respect to titanium is almost independent of the annealing temperature.
Published Version
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