Island formation on 0.1 at.% La-doped SrTiO3(1 0 0) at elevated temperatures under reducing conditions

Annealing of 0.1 at.% La-doped SrTiO3(1 0 0) under reducing conditions (pO2⩽10−8 mbar) between 1000 and 1300 °C for 2 h leads to the formation of islands, which coalesce yielding agglomerates with characteristic dimensions of several micrometers after 40 h. Microscopic (scanning electron microscopy, scanning tunneling microscopy) and spectroscopic techniques (metastable impact electron spectroscopy, ultraviolet photoelectron spectroscopy, scanning tunneling spectroscopy, depth profile Auger electron spectroscopy) were used to reveal the reaction mechanism. Under these experimental conditions the sublimation of titanium from the surface takes place. The islands contain only Ti (40 at.%) and O (60 at.%). They show metallic-like behaviour and consist of Ti2O3. The island formation results from the creation of oxygen vacancies on the surfaces followed by a Ti depletion in the surface region up to a depth of about 8 nm.