A5005243818- Ferroelectric and Piezoelectric Materials
- Multiferroics and related materials
- Electronic and Structural Properties of Oxides
- Magnetic and transport properties of perovskites and related materials
- Semiconductor materials and devices
- Advanced Condensed Matter Physics
- Advanced Electron Microscopy Techniques and Applications
- Nanowire Synthesis and Applications
- Quantum Dots Synthesis And Properties
- Advancements in Battery Materials
- Semiconductor materials and interfaces
- Advancements in Semiconductor Devices and Circuit Design
- Electron and X-Ray Spectroscopy Techniques
- Photonic and Optical Devices
- ZnO doping and properties
- Integrated Circuits and Semiconductor Failure Analysis
- Gas Sensing Nanomaterials and Sensors
- Semiconductor Quantum Structures and Devices
- Graphene research and applications
- Acoustic Wave Resonator Technologies
- Chalcogenide Semiconductor Thin Films
- Perovskite Materials and Applications
- Nanomaterials for catalytic reactions
- Advancements in Solid Oxide Fuel Cells
- Photonic Crystals and Applications
Swiss Federal Laboratories for Materials Science and Technology
2015-2024
Paul Scherrer Institute
2021
Swiss Light Source
2021
University of Geneva
2021
IBM Research - Zurich
2015-2020
Johannes Kepler University of Linz
2016
ETH Zurich
2006-2014
Lawrence Berkeley National Laboratory
2008-2012
Board of the Swiss Federal Institutes of Technology
2012
University of Antwerp
2003-2010
Although the physics of materials at surfaces and edges has been extensively studied, movement individual atoms an isolated edge not directly observed in real time. With a transmission electron aberration-corrected microscope capable simultaneous atomic spatial resolution 1-second temporal resolution, we produced movies dynamics carbon hole suspended, single layer graphene. The rearrangement bonds beam-induced ejection are recorded as grows. We investigated mechanism reconstruction...
We present a transmission electron microscopy investigation of graphene membranes, crystalline foils with thickness only 1 atom. By using aberration-correction in combination monochromator, 1-A resolution is achieved at an acceleration voltage 80 kV. The low crucial for the stability these membranes. As result, every individual carbon atom field view detected and resolved. observe highly lattice along occasional point defects. formation annealing Stone-Wales defects observed situ. Multiple...
Piezoelectric materials, which convert mechanical to electrical energy and vice versa, are typically characterized by the intimate coexistence of two phases across a morphotropic phase boundary. Electrically switching one other yields large electromechanical coupling coefficients. Driven global environmental concerns, there is currently strong push discover practical lead-free piezoelectrics for device engineering. Using combination epitaxial growth techniques in conjunction with theoretical...
We present a method to prepare monolayer and multilayer suspended sheets of hexagonal boron nitride (h-BN), using combination mechanical exfoliation reactive ion etching. Ultrahigh-resolution transmission electron microscope imaging is employed resolve the atoms, intensity profiles for reconstructed phase images are used identify chemical nature (boron or nitrogen) every atom throughout sample. Reconstructed distinctly different h-BN multilayers even odd number. Unusual triangular defects...
Using a highly coherent focused electron probe in fifth-order aberration-corrected transmission microscope, we report on resolving crystal spacing less than 50 pm. Based the geometrical source size and residual incoherent axial lens aberrations, an is calculated, which theoretically capable of ideal 47 pm with 29% contrast. Our experimental data show Ge 114 imaged 11%-18% contrast at 60%-95% confidence level, providing first direct evidence for sub-50-pm resolution annular dark-field...
We report the formation of a novel ferromagnetic state in antiferromagnet ${\mathrm{BiFeO}}_{3}$ at interface with ferromagnet ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$. Using x-ray magnetic circular dichroism Mn and Fe ${L}_{2,3}$ edges, we discovered that development this spin structure is strongly associated onset significant exchange bias. Our results demonstrate directly related to an electronic orbital reconstruction interface, which supported by linearly polarized...
We report direct experimental evidence for a room-temperature, $\ensuremath{\sim}130\text{ }\text{ }\ensuremath{\mu}\mathrm{C}/{\mathrm{cm}}^{2}$ ferroelectric polarization from the tetragonal-like ${\mathrm{BiFeO}}_{3}$ phase. The physical origin of this remarkable enhancement has been investigated by combination x-ray absorption spectroscopy, scanning transmission electron microscopy, and first principles calculations. A large strain-induced Fe-ion displacement relative to oxygen...
The control of material interfaces at the atomic level has led to novel interfacial properties and functionalities. In particular, study polar discontinuities between complex oxides lies frontier modern condensed matter research. Here we employ a combination experimental measurements theoretical calculations demonstrate bulk property, namely ferroelectric polarization, heteroepitaxial bilayer by precise atomic-scale interface engineering. More specifically, is achieved exploiting valence...
Abstract Direct epitaxial growth of III-Vs on silicon for optical emitters and detectors is an elusive goal. Nanowires enable the local integration high-quality III-V material, but advanced devices are hampered by their high-aspect ratio vertical geometry. Here, we demonstrate in-plane monolithic InGaAs nanostructure p-i-n photodetector Si. Using free space coupling, photodetectors a spectral response from 1200-1700 nm. The 60 nm thin devices, with footprints as low ~0.06 μm 2 , provide...
Semiconductor quantum dots have long been considered artificial atoms, but despite the overarching analogies in strong energy-level quantization and single-photon emission capability, their spectrum is far broader than typical atomic lines. Here, by using ab-initio molecular dynamics for simulating exciton-surface-phonon interactions structurally dynamic CsPbBr3 dots, followed single dot optical spectroscopy, we demonstrate that line-broadening these primarily governed coupling of excitons...
Nanocrystal superlattices (NC SLs) have long been sought as promising metamaterials, with nanoscale-engineered properties arising from collective and synergistic effects among the constituent building blocks. Lead halide perovskite (LHP) NCs come across outstanding candidates for SL design, they demonstrate light emission, known superfluorescence, in single- multicomponent SLs. Thus far, LHP only assembled single-component SLs or coassembled dielectric NC blocks acting solely spacers between...
We report a facile colloidal synthesis of gallium (Ga) nanoparticles with the mean size tunable in range 12–46 nm and excellent distribution as small 7–8%. When stored under ambient conditions, Ga remain stable for months due to formation native passivating Ga-oxide layer (2–3 nm). The mechanism is elucidated using nuclear magnetic resonance spectroscopy molecular dynamics simulations. Size-dependent crystallization melting temperature 98–298 K are studied X-ray powder diffraction, specific...
Various transition metal (TM) doped zinc oxide nanoparticles with the composition TMxZn1−xO (TM = V, Mn, Fe, Co, and Ni; x 0.01−0.3) were prepared by a microwave-assisted nonaqueous sol−gel route in benzyl alcohol within few minutes. The high doping levels range 20−30 atom % achieved for Co Fe provide promising opportunity to study magnetic properties of such potential diluted semiconductors. However, only Fe0.2Zn0.8O was ferromagnetic at room temperature. Co-doped sample showed Curie−Weiss...
Abstract The hydrogenation of CO 2 into value‐added chemicals is one the most investigated methods to reduce emissions in atmosphere and thereby contributes a sustainable chemical industry. Whereas catalytic methanol synthetic hydrocarbons well established, effective selective transformation higher alcohols still challenging. Here, we show that Pd single atoms anchored on surface Fe 3 O 4 are very active for ethanol at 300 °C, even atmospheric pressure. By comparing various Pd/MO x...
Barium titanate (BaTiO3) has become an attractive material to extend the functionalities of silicon photonics platform because its large Pockels coefficient more than 1000 pm/V. BaTiO3 integrated epitaxially on silicon-on-insulator substrates can be structured in passive and electro-optic photonic devices using slot-waveguide geometries, both which have been demonstrated. However, all demonstrated so far suffer from high optical propagation losses ∼40–600 dB/cm, limits their performance...