Integration of functional complex oxide nanomaterials on silicon

The combination of standard wafer-scale semiconductor processing with the properties of functional oxides opens up to innovative and more efficient devices with high value applications which can be produced at large scale. This review uncovers the main strategies that are successfully used to monolithically integrate functional complex oxide thin films and nanostructures on silicon: the chemical solution deposition approach (CSD) and the advanced physical vapor deposition techniques such as oxide molecular beam epitaxy (MBE). Special emphasis will be placed on complex oxide nanostructures epitaxially grown on silicon using the combination of CSD and MBE. Several examples will be presented, with a particular stress on the control of interfaces and crystallization mechanisms on epitaxial perovskite oxide thin films, nanostructured quartz thin films, and octahedral molecular sieve nanowires. This review enlightens on the potential of complex oxide nanostructures and the combination of both chemical and physical elaboration techniques for novel oxide-based integrated devicesAC acknowledges the financial support from 1D-RENOX project (Cellule Energie INSIS-CNRS). J.M.V.-F. also acknowledges MINECO for support with a Ph.D. grant of the FPI program. We thank David Montero and L. Picas for technical support. We also thank P. Regreny, C. Botella, J.B. Goure for technical assistance on the Nanolyon technological platform. We acknowledge MICINN (MAT2008-01022 MAT2011-28874-c02-01 and MAT2012-35324), Consolider NANOSELECT (CSD2007-00041), Generalitat de Catalunya (2009 SGR 770 and Xarmae), and EU (HIPERCHEM, NMP4-CT2005-516858) projects. The HAADF-STEM microscopy work was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. This research was supported by the European Research Council (ERC StG-2DTHERMS), Ministerio de Economía y Competitividad of Spain (MAT2013-44673-R) and EU funding Project “TIPS” Thermally Integrated Smart Photonics Systems Ref: 644453 call H2020-ICT-2014-1S

Evaporation-induced self-assembly synthesis of Ni-doped mesoporous SnO₂ thin films with tunable room temperature magnetic properties

Mesoporous Ni-doped SnO₂ thin films synthesized from variable [Ni(II)/Sn(IV)] molar ratios (0 : 100, 5 : 95, 10 : 90, 15 : 85 and 20 : 80), thicknesses in the range of 100-150 nm, and average pore sizes lower than 10 nm were obtained through a sol-gel based self-assembly process using Pluronic P-123 as a structure-directing agent. Grazing incidence X-ray diffraction experiments indicate that the films mostly possess a tetragonal SnO₂ structure with Ni²+ in substitutional positions, although energy-dispersive X-ray analyses also reveal the occurrence of small NiO clusters in the films produced from high [Ni(II)/Sn(IV)] molar ratios (corresponding to a Ni amount of 8.6 at%). X-ray photoelectron spectroscopy experiments indicate the lack of metallic Ni and the occurrence of oxygen vacancies in the mesoporous films. Interestingly, the magnetic properties of these mesoporous films significantly vary as a function of the doping percentage. The undoped SnO₂ films exhibit a diamagnetic behavior, whereas a clear paramagnetic signal dominates the magnetic response of the Ni-doped mesoporous films, probably due to the presence of NiO as a secondary phase. A small ferromagnetic-like contribution superimposed to the paramagnetic background is observed for samples with high Ni contents, possibly stemming from the combined effect from Ni incorporation and the occurrence of oxygen vacancies

Distance Dependence of the Photocatalytic Efficiency of TiO 2 Revealed by in Situ Ellipsometry

International audienceSpectroscopic ellipsometry was utilized to follow in situ photodegradation of organic species in the vicinity of TiO2 nanoparticles during UV irradiation. Stacked layers composed of TiO2, mesoporous SiO2, and mixed mesoporous SiO2/TiO2 nanocomposites with controlled thickness and porosity were used as model materials. Lauric acid molecules and poly(vinyl chloride) (PVC) layers were used as model mobile and immobile pollutants, respectively. The local photocatalytic activity was deduced by monitoring the variation of the thickness and refractive index of each independent layer. We show that the photocatalyzed degradation of an organic pollutant takes place only when the latter is located in close vicinity to the TiO2 nanoparticle surface or can naturally diffuse toward it. As a result, the reaction efficiency is directly related to the organic pollutant diffusion. We also show that the distance of photocatalysis efficiency (ds) at which radical intermediates are still present and active is <10 nm from the TiO2 surface under the conditions of the experiments. This was confirmed by the fact that an immobile condensed organic phase such as PVC was protected from the photocatalytic degradation when separated from the TiO2 by a 20 nm layer of mesoporous silica

Chemical synthesis of oriented ferromagnetic LaSr-2 × 4 manganese oxide molecular sieve nanowires

We report a chemical solution based method using nanoporous track-etched polymer templates for producing long and oriented LaSr-2 x 4 manganese oxide molecular sieve nanowires. Scanning transmission electron microscopy and electron energy loss spectroscopy analyses show that the nanowires are ferromagnetic at room temperature, single crystalline, epitaxially grown and self-aligned

Polymer assisted deposition of epitaxial oxide thin films

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Semiconducting Films: Electric and Mechanical Switching of Ferroelectric and Resistive States in Semiconducting BaTiO 3- δ Films on Silicon (Small 39/2017)

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Epitaxy of SrTiO 3 on Silicon: The Knitting Machine Strategy

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