Geometric structure and chemical composition of SrTiO3 surfaces heated under oxidizing and reducing conditions

SrTiO3(1 0 0) single crystals with two different donor dopant concentrations were heated at 1300 °C in synthetic air and ultrahigh vacuum, respectively, and afterwards studied with atomic force microscopy to characterize the surface topology. Depth profiling measurements utilizing Auger electron spectroscopy yielded information on the chemical composition of secondary phases forming on top of the surface during annealing and of the surface region between them. Under oxidizing conditions a formation of SrOx insulating islands appearing on top of the surface is observed which strongly depends on crystal doping. Between these islands the formation of an additional phase is found. In contrast to the air heated surfaces no material enrichment and no SrOx formation is found under reducing conditions.