Thermal stability of epitaxial SrRuO_(3) films as a function of oxygen pressure

摘要

The thermal stability of electrically conducting SrRuO_(3) thin films grown by pulsed-laser deposition on (001) SrTiO_(3) substrates has been investigated by atomic force microscopy and reflection high-energy electron diffraction (RHEED) under reducing conditions (25-800℃ in 10~(-7)-10~(-2) Torr O_(2)). The as-grown SrRuO_(3) 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℃ 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 SrRuO_(3). 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 SrRuO_(3).