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Off‐Stoichiometry of Magnetron Sputtered Ba 1− x Sr x TiO 3 Thin Films
Author(s) -
Rachut Karsten,
Bayer Thorsten J. M.,
Wolff Jan O.,
Kmet Brigita,
Benčan Andreja,
Klein Andreas
Publication year - 2019
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201900148
Subject(s) - stoichiometry , x ray photoelectron spectroscopy , analytical chemistry (journal) , materials science , perovskite (structure) , sputter deposition , thin film , cavity magnetron , titanium , transmission electron microscopy , phase (matter) , barium , strontium , sputtering , mineralogy , crystallography , chemistry , nuclear magnetic resonance , nanotechnology , metallurgy , physics , organic chemistry , chromatography
Barium strontium titanate thin films with different Ba/Sr ratios deposited by radio‐frequency magnetron sputtering are studied with respect to their composition using in situ X‐ray photoelectron spectroscopy. The deposited samples can be described as either titanium‐rich or stoichiometric, with cation B/A ratios (i.e., ratios between the Ti and (Ba + Sr) concentrations) of 1.2–1.6 or 0.7–1.0, respectively. Volume sensitive compositional analysis using transmission electron microscopy shows a non‐stoichiometry, which is less pronounced than at the surface. X‐ray diffraction only shows cubic perovskite reflections. Together with photoelectron binding energy differences and full widths at half maxima of the Ti 2p and O 1s emissions, this indicates that all films consist of a single phase. The relation between oxygen concentration and B/A ratio further indicates that the deviation of stoichiometry is accommodated by removal or insertion of (Ba,Sr)O. The higher variation of (Ba,Sr)O content near the surface as compared to the bulk may be associated to an increased strain, which is proposed to contribute to surface roughening.