Growth-related stress and surface morphology in homoepitaxial SrTiO3 films

The lattice parameter and surface morphology of homoepitaxial SrTiO3 films were found to depend on the ambient oxygen pressure during growth. The homoepitaxial layers were grown by pulsed laser deposition with static ambient oxygen pressures of 100, 10, and 1 mTorr. The surface roughness of the films increased with increasing ambient growth pressure. In each case, the measured out-of-plane lattice parameter of the film was larger than that of the substrate. The mismatch between film and substrate increased with decreasing growth pressure. Compressive stresses of ∼0.28, 1.2, and 2.0 GPa were determined for homoepitaxial SrTiO3 layers deposited at 100, 10, and 1 mTorr, respectively.