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STO/BTO Modulated Superlattice Multilayer Structures with Atomically Sharp Interfaces
Author(s) -
Petrov Peter K.,
Zou Bin,
Wang Yiqian,
Perkins James M.,
McComb David W.,
Alford Neil McN.
Publication year - 2014
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201300116
Subject(s) - materials science , superlattice , dielectric , ferroelectricity , transmission electron microscopy , electron energy loss spectroscopy , thin film , strontium titanate , high resolution transmission electron microscopy , thermal stability , microstructure , scanning electron microscope , scanning transmission electron microscopy , spectroscopy , pulsed laser deposition , analytical chemistry (journal) , optoelectronics , nanotechnology , composite material , chemical engineering , chemistry , physics , chromatography , quantum mechanics , engineering
A comparative study is carried out investigating the microstructure and the electrical properties of Ba x Sr 1‐x TiO 3 films with x = (0.25, 0.5, 0.75) deposited as modulated superlattice (SL) multilayer structures by laser ablation on both LaAlO 3 and MgO substrates. The SL structures are examined using high‐resolution transmission electron microscopy and scanning transmission electron microscopy . Their interfaces and chemical composition are investigated using energy dispersive X‐ray spectroscopy, complemented with electron energy loss spectra analysis performed to give insight to the local chemistry, structure and bonding. It is found that all modulated SL samples consisted of continuous well defined 1 nm SrTiO 3 and 4 nm BaTiO 3 layers. When modulated SL multilayered structures are compared with their single target deposited equivalents, they exhibit similar electrical properties (e.g. dielectric constant and dielectric loss) but undergo phase transition in a broader temperature region. A very important observation is that the oxygen K‐edges in SrTiO 3 and BaTiO 3 layers are distinctive. Therefore it can be used as finger‐print signature for analysis of ultra‐thin SrTiO 3 /BaTiO 3 layers and their interfaces. Finally it is demonstrated that by varying the modulation period it is possible to develop structures with engineered ferroelectric properties and improved thermal stability.