A5085432546- GaN-based semiconductor devices and materials
- Laser-Plasma Interactions and Diagnostics
- Laser-Matter Interactions and Applications
- Advanced X-ray Imaging Techniques
- ZnO doping and properties
- Particle Accelerators and Free-Electron Lasers
- Ga2O3 and related materials
- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Molecular Physics
- Advanced Electron Microscopy Techniques and Applications
- Semiconductor Quantum Structures and Devices
- Laser Design and Applications
- Semiconductor materials and devices
- Ion-surface interactions and analysis
- Spectroscopy and Quantum Chemical Studies
- Laser-induced spectroscopy and plasma
- Metal and Thin Film Mechanics
- Advanced Fiber Laser Technologies
- Lipid Membrane Structure and Behavior
- Silicon and Solar Cell Technologies
- Silicon Nanostructures and Photoluminescence
- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Advancements in Semiconductor Devices and Circuit Design
- Near-Field Optical Microscopy
Institut für Nanophotonik
2025
Extreme Light Infrastructure Beamlines
2019-2025
Czech Academy of Sciences, Institute of Physics
2020-2022
Center for Biomolecular Nanotechnologies
2020
Czech Technical University in Prague
2020
Czech Academy of Sciences
2019
University of Göttingen
2006-2013
Analog Devices (United States)
2002
The experimental characterization of the spatial and temporal coherence properties free-electron laser in Hamburg (FLASH) at a wavelength 8.0 nm is presented.Double pinhole diffraction patterns single femtosecond pulses focused to size about 10×10 μm 2 were measured.A transverse length 6.2 ± 0.9 horizontal 8.7 1.0 vertical direction was determined from most coherent pulses.Using split delay unit time produced same operation conditions FLASH measured be 1.75 0.01 fs.From our experiment we...
We present experimental results obtained at a user-oriented XUV beamline implemented the ELI Beamlines facility. The coherent radiation is produced via high harmonic generation in gases loose focusing geometry. designed to be driven by 1 kHz, 100 mJ, 20 fs pulses centered wavelength of 830 nm. Results such as spectra, beam wavefront and pulse energy during commissioning with commercial 5 40 laser system are presented. A unique spectrometer for source characterization reach very sensitivity...
ABSTRACT In this work, we demonstrate the integration of a flat liquid jet sample delivery system into compact soft x‐ray absorption spectrometer using table‐top laser‐induced plasma source. A high‐speed sheet is formed by collision two cylindrical jets. This micrometer‐thin lamella can ideally be utilized for transmission‐mode spectroscopy krypton emission. Detailed analysis jet's thickness profile achieved applying Lambert–Beer's law. Measurements on water, focusing oxygen K‐edge, reveal...
In this work, experimentally measured characteristics of a kilohertz laser-driven Cu plasma X-ray source that was recently commissioned at the ELI Beamlines facility are reported. The can be driven either by an in-house developed high-contrast sub-20 fs near-infrared terawatt laser based on optical parametric chirped-pulse amplification technology or more conventional Ti:sapphire delivering 12 mJ and 45 pulses. parameters obtained with two driving lasers compared. A photon flux order up to...
We report the commissioning of novel holography endstation for P10 coherence beamline at PETRA III DESY. The experimental imaging scheme is based on a highly coherent and divergent (cone) beam illumination, achieved by fixed‐curvature focusing mirrors with additional spatial filtering x‐ray waveguides. optical elements along path instrument in are described. First results shown.
We study extreme-ultraviolet wave propagation within optically thick nanostructures by means of high-resolution coherent diffractive imaging using high-harmonic radiation. Exit waves from different objects are reconstructed phase retrieval algorithms, and shown to be dominated waveguiding the sample. The experiments provide a direct visualization guided modes, demonstrate that multiple scattering is generic feature in extruded nanoscale geometries. observations successfully reproduced...
Electrical-transport properties of ferromagnetic GaGdN layers grown by molecular-beam epitaxy on highly resistive 6H-SiC(0001) substrates have been investigated. It is found that doping with low concentrations Gd increases the resistivity several orders magnitude as compared to unintentionally doped GaN. In measurable temperature range between 5 and 120 K two different dependences (${T}^{\ensuremath{-}1/2}$ ${T}^{\ensuremath{-}1/4}$) are observed, both which characteristic...
In this study, we report on the incorporation of dilute Gd amounts into GaN films grown by molecular beam epitaxy. A combination x-ray fluorescence with absorption spectroscopic techniques enabled us to examine not only distribution rare earth atoms in matrix but also short-range structural order. Our results show a trivalent state tetrahedral coordination, thus substituting Ga wurtzite structure.
We report on a characteristic photoluminescence feature of the substitutional Mn in high quality GaMnN layers. The lattice site was identified using atom localization by channeling enhanced microanalysis with transmission electron microscope. It shows that 96.5%±5.0% atoms are incorporated Ga site. In appears at 1.41 eV phonon sideband related to GaN matrix. temperature evolution is an intra-atomic transition and it assigned internal E5→T52 Mn3+ ion. assignment supported absorption...
We report on the status of a users' end-station, MAC: Multipurpose station for Atomic, molecular and optical sciences Coherent diffractive imaging, designed studies structure dynamics matter in femtosecond time-domain. MAC is located E1 experimental hall high harmonic generation (HHG) beamline ELI Beamlines facility. The extreme ultraviolet beam from HHG can be used at end-station together with synchronized pump (which will cover NIR/Vis/UV or THz range) time-resolved experiments different...
The spatial coherence of free-electron laser radiation in the water window spectral range was studied, using third harmonic (λ 3rd = 2.66 nm) DESY's Free-electron LASer Hamburg (FLASH).Coherent single pulse diffraction patterns 1,2-Dioleoyl-sn-glycero-3phosphocholine (DOPC) multilamellar lipid stacks have been recorded.The intensity histogram speckle pattern around first lamellar Bragg peak, corresponding to d 5 nm periodicity stack, reveals an average number transverse modes M 3.0...
Abstract With the aim of understanding observed roomtemperature giant magnetic moment highly diluted GaGdN reported in literature GaGdN, GaGdN:Si and GaGdN:H have been grown by molecular beam epitaxy (MBE) Gd concentration is between 10 16 21 cm 3 . All samples are ferromagnetic at 300 K as measured SQUID very high saturation this type confirmed our experiments. co‐doping hydrogen or silicon we were able to decrease increase strength moments layers, respectively. findings indicate that...
In this paper, the authors present characterization experiments of a 20 fs vacuum ultraviolet beam from high harmonic generation source. The hits silicon sample and passes triple reflection gold polarizer located inside an ultrahigh chamber. polarizer’s Malus curve was obtained; total acquisition time for each point 30 s. This aims to be first time-resolved user station dedicated ellipsometry. is generated by 12 mJ, 1 kHz, fs, in-house-developed laser detected back-illuminated charge-coupled device.
A silicon bipolar process for RF and microwave applications, which features 25-GHz double-polysilicon self-aligned npn transistors with 5.5-V BV/sub CEO/, optional 0.7-/spl mu/m NMOS p/sup +/ polysilicon gate switch lateral pnp transistors, high low valued resistors, polysilicon-to-n/sup plug capacitors, is described. The utilize nitride-oxide composite spacers formed using sacrificial TEOS spacers. capabilities of the up to several GHz are demonstrated by fabricating characterizing...
We study the nonequilibrium shape fluctuations in fluorescence labeled phospholipid multibilayers composed of model lipid DOPC and well-known dye Texas red, driven out equilibrium by short laser pulses. The temporal evolution bilayer undulations after excitation was recorded time resolved x-ray diffraction. Already at moderate peak intensities (${P}_{p}\ensuremath{\le}{10}^{5}\text{ }\text{ }{\mathrm{W}/\mathrm{cm}}^{2}$), pulsed illumination leads to significant changes undulation modes a...
GaMnN layers have been grown by MBE on Si(111) in a wide range of growth conditions. For different substrate temperatures the structural and composition dependence has studied as function Mn supply. We find that at regular temperature incorporation into layer is low difficult to control. Only reduced 650 °C under N-rich conditions it possible grow homogeneous if supply below 15% total metal flux. The efficiency this about 30%, which corresponds maximum content diluted 5%. Above critical...
Abstract Imaging of extended defects at atomic resolution using high‐resolution transmission electron micrography (HRTEM) is problematic due to the lens aberrations an uncorrected microscope and loss phase during recording images. As a result, techniques measure strain fields these can only be applied under distinct well‐controlled conditions sometimes in narrow window specimen thickness imaging conditions. Using combination focal series reconstruction numerically correction a‐posteriori...
We present a time-resolved infrared (IR) pump and extreme-ultraviolet (XUV) probe diffraction experiment to investigate ultrafast structural dynamics in colloidal crystals with picosecond resolution. The was performed at the FLASH facility DESY fundamental wavelength of 8 nm. In our experiment, temporal changes Bragg peaks were analyzed, their frequency components calculated using Fourier analysis. Periodic modulations crystal localized about 4--5 GHz. Based on Lamb theory, theoretical...
Three main paths are being developed within the ELI research program for transforming driving laser pulses into bursts of bright short wavelength radiation: high-order harmonic generation in gases, plasma X-ray sources and based on relativistic electron beams accelerated plasma. For each these areas, dedicated beamlines built to provide a unique combination scientific community. The application has well-defined balance between fundamental science applications different fields technology....
Experimentally measured characteristics of a kHz laser-driven Cu plasma X-ray source that was recently commissioned at ELI Beamlines facility are reported. The can be driven either by an in-house developed high contrast sub-20 fs near-infrared TW laser based on optical parametric chirped-pulse amplification technology, or more conventional Ti:sapphire delivering 12 mJ, 45 pulses. parameters obtained with the two driving lasers compared. Measured photon flux order up to 10^{12} K{\alpha}...
Quantitative lattice-site determination of manganese in spatially inhomogeneous low-temperature GaN is performed by channeling enhanced microanalysis. The technique allows one to measure the substitutional-to-interstitial ratio at a spatial resolution suitable study individual single-crystalline columns. Numerical fitting full dynamical Bloch wave calculations yields fraction (95.6±6.3)% incorporated on substitutional sites.
A compact tabletop plasma X-ray source (PXS) generating hard radiation in the energy range between 3 keV and 30 has been installed commissioned at ELI beamlines, experimental hall E1, utilizing ELI's high repetition-rate / pulse-energy fs-laser system L1. Together with TREX endstation IR-pump X-ray-probe stroboscopic approaches to time-resolved studies can be conducted.
A compact undulator-based soft X-ray radiation source furnishing the laser wakefield electron acceleration concept is currently being developed at ELI-Beamlines in Czech Republic. It will bring to user community a high-repetition-rate (up 50 Hz) enable high-temporal-resolution pump-probe experiments, combined with XANES spectroscopy, high-resolution microscopy, investigations of biological molecules and chemical reactions, evaluation multilayer optics, as well coherent applications like...
Abstract GaMnN is a prototypical GaN‐based dilute magnetic semiconductor (DMS) and its potential as room temperature ferromagnetic material still controversial question to be answered. Diluted layers with Mn concentrations up several percent have been grown by plasma‐assisted MBE on MOVPE‐GaN templates either p‐Si(111) or Al 2 O 3 (0001) substrates. None of the samples reported here shows second phase precipitates in XRD TEM analysis. However different composition distributions evidenced EDX...