Unconventional ferroelectricity exhibited by hafnia-based thin films, robust at nanoscale sizes, presents tremendous opportunities in nanoelectronics. However, the exact nature of polarization switching remains controversial. We investigated La0.67Sr0.33MnO3/Hf0.5Zr0.5O2 capacitor interfaced with various top electrodes while in situ electrical biasing using atomic resolution microscopy with direct oxygen imaging, as well as synchrotron nanobeam diffraction. When the top electrode is oxygen reactive, we clearly show reversible oxygen vacancy migration with electrodes being the source and sink of oxygen, and the dielectric layer acting as a fast conduit at millisecond timescales. With non-reactive top electrodes and at longer time scales (seconds), the dielectric layer also acts as an oxygen source/sink. Our results show that ferroelectricity in hafnia-based thin films is unmistakably intertwined to oxygen voltammetry.

Hard X-ray lens-less microscopy raises hopes for a non-invasive quantitative imaging, capable of achieving the extreme resolving power demands of nanoscience. However, a limit imposed by the partial coherence of third generation synchrotron sources restricts the sample size to the micrometer range. Recently, X-ray ptychography has been demonstrated as a solution for arbitrarily extending the fi eld of view without degrading the resolution. Here we show that ptychography, applied in the Bragg geometry, opens new perspectives for crystalline imaging. The spatial dependence of the three-dimensional Bragg peak intensity is mapped and the entire data subsequently inverted with a Bragg-adapted phase retrieval ptychographical algorithm. We report on the image obtained from an extended crystalline sample, nanostructured from a silicon-on-insulator substrate. The possibility to retrieve, without transverse size restriction, the highly resolved three-dimensional density and displacement fi eld will allow for the unprecedented investigation of a wide variety of crystalline materials, ranging from life science to microelectronics.

Numerous imaging methods have been developed over recent years in order to study materials at the nanoscale. Within this context, scanning X‐ray diffraction microscopy has become a routine technique, giving access to structural properties with sub‐micrometre resolution. This article presents an optimized technique and an associated software package which have been implemented at the ID01 beamline (ESRF, Grenoble). A structural scanning probe microscope with intriguing imaging qualities is obtained. The technique consists in a two‐dimensional quick continuous mapping with sub‐micrometre resolution of a sample at a given reciprocal space position. These real space maps are made by continuously moving the sample while recording scattering images with a fast two‐dimensional detector for every point along a rocking curve. Five‐dimensional data sets are then produced, consisting of millions of detector images. The images are processed by the user‐friendly X‐ray strain orientation calculation software (XSOCS), which has been developed at ID01 for automatic analysis. It separates tilt and strain and generates two‐dimensional maps of these parameters. At spatial resolutions of typically 200–800 nm, this quick imaging technique achieves strain sensitivity below Δa/a = 10−5 and a resolution of tilt variations down to 10−3° over a field of view of 100 × 100 µm.

The intriguing thermophysical properties of CeB6 have been subject to investigation for more than 20 years. In particular, an exotic ground state, phase IV, emerges under doping with La. We report resonant x-ray scattering results on the order parameter symmetries in phase IV of Ce0.7La0.3B6, which condenses below T(IV)=1.5 K. The results reveal a degree of mesoscopic 5d dipole antiferromagnetic order, with propagation vector Q0=(1/2 1/2 1/2), both below and above T(IV). Below T(IV), this polarization coexists with long-range 4f antiferro-octupole (AFO) order also at Q0. The marked differences in temperature dependence and spatial correlation suggest a state of order parameter segregation at low temperature. A simple model of AFO order, consistent with the polarization dependent azimuth symmetries, the Bragg angle, and temperature dependence is given.

This work is focused on synthesis, characterization, and determination of main parameters of the multilayer P123 templated TiO 2 films. The mesoporous multilayer thin films consist of TiO 2 nanoparticles on the F-doped SnO 2 (FTO) conductive glass substrates. The films were grown by implementing the protocol of supramolecular templating with the amphiphilic triblock copolymer, Pluronic P123. The templated multilayer films were manufactured by repeated dip coating followed by the thermal treatment at 350 °C for 2 h after deposition of each layer. It was found that the multilayer preparation technique at 350 °C has serious limitations. The structure does not further increase its specific surface area (roughness factor) after deposition of more than 3-5 layers. The new surface area added by deposition of the top layer is compensated by the reduction of the surface area lost due to the sintering of the bottom layers. The careful review of the analytical data suggests that the morphology of the P123 templated TiO 2 structure is likely the tightest arrangement of randomly positioned particles of a certain size on a given pore diameter. The bulk material consists of pores evenly formed in all directions while a denser crust is formed on the surface where the fusion was restricted in one direction at the interface with the air. Subsequent thermal treatments of the multilayer films were applied to improve the anatase crystallinity while keeping the open morphology and small particle size. The morphological changes of the mesoporous structure during the subsequent thermal treatment at 425-540 °C were investigated.

TiO2(B) mesoporous thin films were grown in two steps on the F-doped SnO2 conductive glass substrates. In the first step, a small amount of H3PO4, corresponding to 0.15−0.375 wt % P on TiO2 basis, was introduced into concentrated HCl which was subsequently used for hydrolysis of titanium ethoxide. The hydrolyzed colloidal TiO2 suspension was further mixed with a 1-butanol solution of the amphiphilic triblock copolymer Pluronic P123. The obtained precursor mixture was used for dip coating of FTO substrates. To achieve over 1 μm thick films, dip coating (followed by a thermal treatment at 350 °C/2 h) was repeated several times to produce multilayer films. The films consisted of amorphous TiO2 with small amounts of anatase and TiO2(B). The amorphous part was converted into the TiO2(B) in a simple firing step at 500−550 °C. The formation of TiO2(B) phase was accompanied by a significant increase of the film thickness. The films demonstrated unique behavior during the electrochemical lithium insertion that would qualify them for fast battery or electrochromic smart window applications. The efficiency of multiphase TiO2 films in dye sensitized solar cells depends on the composition of individual films: it increases in the series: anatase/amorphous TiO2 < anatase/TiO2(B) < anatase.

For advanced electronic, optoelectronic, or mechanical nanoscale devices a detailed understanding of their structural properties and in particular the strain state within their active region is of utmost importance. We demonstrate that X-ray nanodiffraction represents an excellent tool to investigate the internal structure of such devices in a nondestructive way by using a focused synchotron X-ray beam with a diameter of 400 nm. We show results on the strain fields in and around a single SiGe island, which serves as stressor for the Si-channel in a fully functioning Si–metal–oxide semiconductor field-effect transistor.

We report on the preparation of high performance field-effect transistors (FETs) based on large areas of aligned films of a TTF derivative, namely, tetrakis-(octadecylthio)-tetrathiafulvalene (TTF-4SC18). TTF-4SC18 assembles into one-dimensional stacks in which the long alkyl chains promote intermolecular π−π overlapping due to their extremely closely packed nature. The films were prepared from solution by zone-casting, a simple technique that does not require the use of preoriented substrates. The films were characterized by AFM and X-ray, indicating an extremely high crystalline quality. The TTF molecules are tilted with respect to the substrate surface and are well-aligned in the casting direction. More than 40 FETs were measured, showing a remarkable reproducibility of their performance. The average charge carrier mobility value measured along the casting direction was about 0.006 cm2/V s for a channel length L = 100 μm and about 0.01 cm2/V s for L = 80 μm and L = 50 μm. The FET mobilities determined in the direction perpendicular to the orientation were ca. 1 order of magnitude lower. We found that all the devices after annealing exhibited an enhanced performance with FETs mobilities about 1 order of magnitude higher. The best devices revealed a charge carrier mobility close to 0.1 cm2/V s with an on/off ratio of the order of 104.