Thermal stability of epitaxial SrRuO3 films as a function of oxygen pressure

The thermal stability of electrically conducting SrRuO3 thin films grown by pulsed-laser deposition on (001) SrTiO3 substrates has been investigated by atomic force microscopy and reflection high-energy electron diffraction (RHEED) under reducing conditions (25-800 degreesC in 10(-7)-10(-2) Torr O-2). The as-grown SrRuO3 epitaxial films exhibit atomically flat surfaces with single unit-cell steps, even after exposure to air at room temperature. The films remain stable at temperatures as high as 720 degreesC in moderate oxygen ambients (>1 mTorr), but higher temperature anneals at lower pressures result in the formation of islands and pits due to the decomposition of SrRuO3. Using in situ RHEED, a temperature and oxygen pressure stability map was determined, consistent with a thermally activated decomposition process having an activation energy of 88 kJ/mol. The results can be used to determine the proper conditions for growth of additional epitaxial oxide layers on high quality electrically conducting SrRuO3. (C) 2004 American Institute of Physics.