Microstructuring and layer transfer offer the possibility to create artificial crystal systems with new properties that are not accessible via classical growth approaches. Using remote epitaxy, a team of researchers from China and the IKZ has succeeded in producing thin free-standing oxygen-deficient barium titanate (BaTiO3) films with high flexoelectric coefficients. For this purpose, BaTiO3 films were heteroepitaxially grown with a thickness of up to 90 nm on graphene-passivated germanium substrates using pulsed laser deposition and transferred to flexible polymer substrates after exfoliation. The orientation of the germanium substrates played an important role in the structure of the membranes. The significantly improved flexoelectric properties of the BaTiO3 membranes compared to conventional thin film systems are attributed to the absence of chemical bonds to the polymer substrate and thus to the reduced clamping effect, as well as to the cubic lattice structure of the BaTiO3 films induced by the low-oxygen growth atmosphere. The results show the great potential of such free-standing complex oxide layer membranes for e.g. energy harvesting in flexible devices. They were published in the Journal Nature Communications in May 2022 (https://doi.org/10.1038/s41467-022-30724-7 ).
The work took place within the framework of the Sino-German Joint Lab "Dielectrics" between the IKZ and the School of Electronic Science and Engineering at Xi'an Jiatong University. The aim of the Joint Lab is the research of fundamentals and possible applications of dielectric oxides and 2D materials as well as the education and exchange of students.
More information on the German-Chinese Joint Lab: https://www.ikz-berlin.de/forschung-lehre/joint-labs-support-labs
Further information:
Jutta Schwarzkopf
