A5025382319- Semiconductor Quantum Structures and Devices
- Ferroelectric and Piezoelectric Materials
- Multiferroics and related materials
- Acoustic Wave Resonator Technologies
- Semiconductor materials and interfaces
- GaN-based semiconductor devices and materials
- Advanced Semiconductor Detectors and Materials
- Semiconductor materials and devices
- Integrated Circuits and Semiconductor Failure Analysis
- ZnO doping and properties
- Electron and X-Ray Spectroscopy Techniques
- Quantum Dots Synthesis And Properties
- Electronic and Structural Properties of Oxides
- Nanowire Synthesis and Applications
- Ga2O3 and related materials
- Chalcogenide Semiconductor Thin Films
- Crystallography and Radiation Phenomena
- Magnetic and transport properties of perovskites and related materials
- Advanced Electron Microscopy Techniques and Applications
- Advanced X-ray Imaging Techniques
- Ion-surface interactions and analysis
- Microwave Dielectric Ceramics Synthesis
- Surface Roughness and Optical Measurements
- Silicon and Solar Cell Technologies
- Advanced Chemical Physics Studies
Leibniz Institute for Crystal Growth
2015-2025
EV Group (Austria)
2023
Forschungsverbund Berlin
2022
Berlin Heart (Germany)
2015
University of Nottingham
2014
Chalmers University of Technology
2014
Cairo University
2014
Technische Universität Berlin
2008
Humboldt-Universität zu Berlin
1997-2005
Fritz Haber Institute of the Max Planck Society
1991-1998
The x-ray scattering from relaxed heteroepitaxial layers with the misfit dislocations randomly distributed at interface between layer and substrate is analyzed theoretically experimentally. profiles of x-ray-diffraction peaks reciprocal space maps intensity are measured simulated for several structures in a wide range dislocation densities. At large densities, peak position governed by mean distortions width due to mean-square variations distortions. widths calculated uncorrelated...
Abstract Epitaxial β‐Ga 2 O 3 layers have been grown on (100) substrates using metal‐organic vapor phase epitaxy. Trimethylgallium and pure oxygen or water were used as precursors for gallium oxygen, respectively. By oxidant, we obtained nano‐crystals in form of wires agglomerates although the growth parameters varied wide range. With an smooth homoepitaxial under suitable conditions. Based thermodynamical considerations gas published ab initio data catalytic action surface discuss...
For the first time, n-type homoepitaxial semiconducting β-Ga<sub>2</sub>O<sub>3</sub> layers were attained by MOVPE.
The lattice parameters of three perovskite-related oxides have been measured with high precision at room temperature. An accuracy the order 10(-5) has achieved by applying a sophisticated high-resolution X-ray diffraction technique which is based on modified Bond method. results cubic SrTiO(3) [a = 3.905268 (98) Å], orthorhombic DyScO(3) 5.442417 (54), b 5.719357 (52) and c 7.904326 NdGaO(3) 5.428410 5.498407 (55) 7.708878 (95) Å] are discussed in view possible systematic errors as well...
We present a systematic study on the influence of miscut orientation structural and electronic properties in homoepitaxial growth off-oriented β-Ga2O3 (100) substrates by metalorganic chemical vapour phase epitaxy. Layers grown with 6° toward [001¯] direction show high electron mobilities about 90 cm2 V−1 s−1 at concentrations range 1–2 × 1018 cm−3, while layers under identical conditions but [001] exhibit low around 10 s−1. By using high-resolution scanning transmission microscopy atomic...
Anisotropic surface diffusion and strain are used to explain the formation of three-dimensional (In,Ga)As quantum dot lattices. The characteristics surface, coupled with elastic anisotropy matrix, provides an excellent opportunity influence positions. In particular, dots that laterally organized into long chains or chessboard two-dimensional arrays vertically strict vertical ordering is inclined sample normal accurately predicted observed.
Magnetic circular dichroism in the extreme ultraviolet (XUV) spectral range is a powerful technique for element-specific probing of magnetization multicomponent magnetic alloys and multilayers. We combine high-harmonic generation source with $\ensuremath{\lambda}/4$ phase shifter to obtain circularly polarized XUV femtosecond pulses ultrafast studies. report on simultaneously measured resonant (MCD) Co Ni at their respective ${M}_{2,3}$ edges Pt its O edge, originating from interface...
We have investigated pseudomorphic ${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ layers grown on Si (001) by means of liquid-phase epitaxy. The been in Stranski-Krastanov growth mode and consist coherent {111}-faceted truncated pyramids exhibiting unique shape a narrow size distribution. Samples with different spatial island densities, i.e., mean island-island distances, grazing incidence small-angle x-ray scattering (GISAXS) atomic force microscopy (AFM). found initial stages...
Abstract Synapses play a vital role in information processing, learning, and memory formation the brain. By emulating behavior of biological synapses, electronic synaptic devices hold promise enabling high‐performance, energy‐efficient, scalable neuromorphic computing. Ferroelectric memristive integrate characteristics both ferroelectric materials present far‐reaching potential as artificial synapses. Here, it is reported on new device silicon, field‐effect memristor, consisting an epitaxial...
Stacking of freestanding membranes enables the formation interfaces beyond what can be obtained with classical heteroepitaxy. In particular, twisted provide unique physical properties not existent in corresponding individual layers. An ideal twist grain boundary yields an in-plane screw-dislocation network, assuming sufficiently strong interactions across interface, for example, via covalent or ionic bonding. Hereby, distance between dislocation lines, that is length scale Moiré pattern, set...
High-resolution x-ray diffraction has been performed on strained SiGe nanoscale islands grown coherently Si(001). Reciprocal space maps show a widely extended ``butterfly''-shaped island reflection and strong diffuse scattering around the substrate reflection. From such intensity Ge content its distribution inside are evaluated. This is done by simulation of for variety models. The shape known from atomic force scanning electron microscopy. only free parameter was distribution, here...
X-ray microdiffraction is used to analyze strain and composition profiles in individual micron-sized SiGe islands grown by liquid phase epitaxy on Si(001) substrates. From the variation of scattered intensity while scanning sample through a focused x-ray beam few $\ensuremath{\mu}\text{m}$ size, an image island distribution created. Using this it possible identify particular select them for analysis one one. The Ge within each obtained from reciprocal space measured several islands. detailed...
The carrier localization phenomenon has been investigated for GaBiAs by photomodulated transmittance (PT) and photoluminescence (PL). In the case of PT measurements, a decrease in energy-gap related signal clearly observed below 180 K. PL spectra broad emission band very sensitive to excitation power found. comparison transition, this is shifted red. recombination time at low temperature decreases from 0.7 0.35 ns with increase energy. All findings are clear evidences strong alloy.
We studied the structural and optical properties of state-of-the-art non-polar bulk GaN grown by ammonothermal method. The investigated samples have an extremely low dislocation density (DD) less than 5 × 104 cm−2, which results in very narrow high-resolution x-ray rocking curves. a c lattice parameters these stress-free were precisely determined using diffraction technique based on modified Bond obtained values are compared to free-standing from different methods sources. observed...
Abstract Herein we investigate a (001)-oriented GaAs 1− x Bi /GaAs structure possessing surface droplets capable of catalysing the formation nanostructures during Bi-rich growth, through vapour-liquid-solid mechanism. Specifically, self-aligned “nanotracks” are found to exist trailing on sample surface. Through cross-sectional high-resolution transmission electron microscopy nanotracks revealed in fact be elevated above by subsurface planar nanowire, initiated mid-way molecular-beam-epitaxy...
Van der Waals (vdW) heterostructures combining layered ferromagnets and other 2D crystals are promising building blocks for the realization of ultracompact devices with integrated magnetic, electronic, optical functionalities. Their implementation in various technologies depends strongly on development a bottom-up scalable synthesis approach allowing realizing highly uniform well-defined interfaces between different 2D-layered materials. It is also required that each material component...
Femtosecond excitation of ${\text{SrRuO}}_{3}$ nanolayers in a ${\text{SrRuO}}_{3}/{\text{SrTiO}}_{3}$ superlattice quenches their ferromagnetism, resulting magnetostriction. The buildup mechanical stress is observed real time by mapping lattice motions via ultrafast x-ray diffraction. A rise 500 fs found for wide range wavelengths. In the ferromagnetic phase, phonon-mediated $({\ensuremath{\sigma}}_{\text{ph}})$ and magnetostrictive $({\ensuremath{\sigma}}_{M})$ components display similar...
We report the growth by molecular beam epitaxy of GaBixAs1−x epilayers on (311)B GaAs substrates. use high-resolution x-ray diffraction (HRXRD), transmission electron microscopy, and Z-contrast imaging to characterize structural properties as-grown material. find that incorporation Bi into GaBiAs alloy, as determined HRXRD, is sizably larger in than (001) epilayers, giving rise reduced band-gap energies obtained optical spectroscopy.
We report a scanning technique, which combines high resolution x-ray diffraction (in reciprocal space) along with submicrometer spatial real space). SiGe∕Si(001) Stranski–Krastanow islands served here as well investigated model system to check the limits of developed method. A set refractive silicon lenses focused beam size down diameter 200nm (full width at half maximum), enables individual micrometer-sized and even smaller islands. By illuminating diverse {111} island side facets, crystal...
Hexagonal GaN (0001) has been grown by a pseudo-HVPE method on β-Ga2O3 (100) using an intermediate low-temperature buffer layer formed in situ NH3 treatment of substrate. A simple for self-separation bulk from the substrate is reported. The structural properties and GaN–β-Ga2O3 interface were investigated high-resolution X-ray diffraction electron microscopy techniques. layers deposited gallium cyanide as transport agent and, source nitrogen. these are compared with those samples sapphire.
Epitaxially strained NaNbO 3 films were grown by liquid-delivery spin metal–organic chemical vapour deposition on several oxide substrates, inducing tensile and compressive lattice strain. High-resolution X-ray diffraction measurements reveal that coherently compressively NdGaO exhibit the orthorhombic c phase. With increasing in-plane strain a first structural phase transition to monoclinic r and, further on, for under rare earth scandates, second aa phase, are observed. Our results in good...