Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 81: Oxide and Insulator Surfaces III

O 81.11: Vortrag

Donnerstag, 3. April 2014, 18:30–18:45, PHY C 213

Stress measurements during PLD growth of BaTiO₃ and SrTiO₃ films on single crystal metal substrates — •Jörg Premper¹, Dirk Sander¹, and Jürgen Kirschner^1,2 — ¹Max-Planck-Institut für Mikrostrukturphysik, D-06120 Halle — ²Institut für Physik, Martin-Luther-Universität, Halle, Germany

The in situ measurement of film stress by the optical 2-beam cantilever deflection technique [1] is used to study the correlation between stress and strain in BaTiO₃ and SrTiO₃ monolayers on Fe, Pd and Pt single crystal surfaces of different orientations. These films are grown by pulsed laser deposition (PLD). We find that the deposition of 18 uc (unit cells) BaTiO₃ on Pt(001) (misfit = −2.3%) leads to a compressive film stress of −4.2 GPa, whereas the deposition of SrTiO₃ (misfit = +0.4%) induces a tensile stress of +1.5 GPa. On Pd(001) the measured film stress for BaTiO₃/Pd(001) is −2.6 GPa (misfit = −3.0%) and for SrTiO₃/Pd(001) −2.0 GPa (misfit = −0.4%). The comparison between measured stress and calculated misfit-induced stress in the framework of continuum elasticity, considering elastic anisotropy, reveals a qualitative agreement between experiment and stress calculations. This identifies epitaxial misfit as one decisive contribution to film stress in BaTiO₃ and SrTiO₃ atomic layers. In contrast, no epitaxial order of BaTiO₃ and SrTiO₃ films on Fe(001) was observed for PLD at 420^∘C by LEED. Still film stress of +2.1 GPa and +3.8 GPa is measured. The results are discussed in view of substrate-mediated strain and the influence of growth conditions.

[1] J. Premper, D. Sander, and J. Kirschner, RSI 83, (2012), 073904