In situ stress measurements during pulsed laser deposition of BaTiO3 and SrTiO3 atomic layers on Pt(001)

We apply the cantilever deflection technique to measure stress in nm thin BaTiO3 and SrTiO3 films during pulsed laser deposition on a Pt(001) single crystal cantilever substrate. We find a compressive film stress of -4.2 GPa for BaTiO3 on Pt(001) (misfit = -2.3%), whereas the deposition of SrTiO3 (misfit = +0.4%) induces a tensile stress of +1.5 GPa. The stress measurements are augmented by in situ low energy electron diffraction experiments which indicate an epitaxial order of the films. We apply continuum elasticity to calculate film stress. We conclude that sign and magnitude of the measured stress are due to the epitaxial misfit between film and substrate, which is -2.3% and +0.4% for BaTiO3 and SrTiO3, respectively. We identify that in addition to misfit also the oxygen partial pressure during PLD film growth influences film stress. PLD growth in an oxygen-free environment leads to factor of two increased tensile stress in SrTiO3 on Pt(001) as compared to growth at Po-2 = 10(-4) mbar. The role of film stoichiometry for film stress is discussed. (C) 2015 Elsevier B.V. All rights reserved.