Study of SrO segregation on SrTiO3(100) surfaces

Annealing as-received lanthanum doped (5 at.% La) SrTiO3(100) single crystals in air at 1300°C for 120 h results in the formation of insulating islands on the surface which have typical dimensions of up to 50 μm. These surfaces are investigated by metastable impact electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), metastable impact electron emission microscopy (MIEEM) and photoelectron emission microscopy (PEEM). The insulating islands consist of stoichiometric SrO. Between these islands an additional Sr enrichment is found in the top surface layers.