Changes in the surface topography and electronic structure of SrTiO3(1 1 0) single crystals heated under oxidizing and reducing conditions

Strontium titanate (SrTiO3) is a promising material for resistive high temperature oxygen sensors. Unfortunately, thermal treatment results in undesirable surface reconstruction and the formation of secondary phases. Each of the three stable surface orientations ((1 0 0), (1 1 0) and (1 1 1)) shows a characteristic reconstruction of the topmost layers. To investigate these changes in more detail, SrTiO3(1 1 0) single crystals were heated up to 1000 °C in ultrahigh vacuum and synthetic air, respectively. Atomic force microscopy (AFM) was applied to characterize the surface topography. Metastable impact electron spectroscopy (MIES) and Auger electron spectroscopy (AES) yielded information on the electronic structure and the chemical composition of the surface and the near surface region. Under all investigated conditions microfaceting of the (1 1 0) surface could be observed resulting in TiO2-terminated ridges.