This study has been carried out in collaboration with NanoChemLab from Montpellier, France. Congratulations to Qianzhe Zhang and Martí Gich for being authors of this work!
Congratulations to Martí Gich, tenured researcher at the N&N group, and the rest of the authors for the recently published paper: Electric and Mechanical Switching of Ferroelectric and Resistive States in Semiconducting BaTiO3–δ Films on Silicon. Moreover, the paper was on the cover of the journal Small (Volume 13, Issue 39, October 18, 2017).
Abstract:
In article number 1701614, Andrés Gómez, Adrián Carretero-Genevrier, and co-workers report a novel approach to integrate epitaxial nanostructured n-type semiconducting BaTiO3−δ films on silicon by combining molecular beam epitaxy and a water-based chemical method. This growth strategy results into epitaxial BaTiO3−δ/La0.7Sr0.3MnO3/SrTiO3/Si columnar nanostructures that enhance the flexoelectric response of the system and enables the control of the ferroelectric polarization and local conductivity (resistive switching) of this functional oxide upon applying a mechanical load.
This work describes the detailed protocol for preparing piezoelectric macroporous epitaxial quartz films on silicon(100) substrates. This is a three-step process based on the preparation of a sol in a one-pot synthesis which is followed by the deposition of a gel film on Si(100) substrates by evaporation induced self-assembly using the dip-coating technique and ends with a thermal treatment of the material to induce the gel crystallization and the growth of the quartz film. The formation of a silica gel is based on the reaction of a tetraethyl orthosilicate and water, catalyzed by HCl, in ethanol.
However, the solution contains two additional components that are essential for preparing mesoporous epitaxial quartz films from these silica gels dip-coated on Si. Alkaline earth ions, like Sr2+act as glass melting agents that facilitate the crystallization of silica and in combination with cetyl trimethylammonium bromide (CTAB) amphiphilic template form a phase separation responsible of the macroporosity of the films. The good matching between the quartz and silicon cell parameters is also essential in the stabilization of quartz over other SiO2 polymorphs and is at the origin of the epitaxial growth.