Surface stability of epitaxial SrRuO3 films

The thermal stability of epitaxial SrRuO3 thin films grown by pulsed-laser deposition (PLD) has been studied by repetitive annealing by steps of 100 °C up to 800 °C under high vacuum and high oxygen pressure conditions. The evolution of chemical state, surface crystallographic structure, surface topography, and the nature of desorption products were studied using electron diffraction, spectroscopy, and scanning probe microscopy. Exposure to atmosphere leads to decomposition of the surface in vacuum at ∼300 °C, despite good crystalline order before annealing. At the same time, films annealed to 700 °C in an oxygen/ozone mixture (10 mTorr) followed by vacuum annealing show no evidence of decomposition below 600 °C. These results reveal that the surface stability of epitaxial SrRuO3 is strongly affected by the presence of surface contaminants after exposure to air. Vibrational spectroscopy identifies these contaminants as adsorbed hydrocarbons. Results are compared with thermodynamic calculations, and implications for oxide electronic device technology are discussed.