80 research outputs found
A Comparison of Stripe Modulations in LaBaCuO and LaNdSrCuO
We report combined soft and hard x-ray scattering studies of the electronic
and lattice modulations associated with stripe order in
LaBaCuO and LaNdSrCuO. We
find that the amplitude of both the electronic modulation of the hole density
and the strain modulation of the lattice is significantly larger in
LaBaCuO than in LaNdSrCuO
and is also better correlated. The in-plane correlation lengths are isotropic
in each case; for LaBaCuO, \AA\
whereas for LaNdSrCuOF,
\AA. We find that the modulations are temperature independent in
LaBaCuO in the low temperature tetragonal phase. In
contrast, in LaNdSrCuO, the amplitude grows
smoothly from zero, beginning 13 K below the LTT phase transition. We speculate
that the reduced average tilt angle in LaBaCuO results
in reduced charge localization and incoherent pinning, leading to the longer
correlation length and enhanced periodic modulation amplitude.Comment: 6 pages, 4 figure
Writing and reading chiral domains in multiferroic DyMnO_3 using soft X-rays
Sizeable b and c components of the 4f moments and pronounced circular
dichroism are observed in the ferroelectric phase of DyMnO_3 by soft X-ray
diffraction at the Dy-M_5 resonance. This points to cycloidal order of the 4f
moments and indicates that inversion-symmetry breaking in this material is not
characteristic of the Mn spins alone. The circular dichroism allows to image
chiral domains that are imprinted on the surface of a DyMnO single crystal,
exploiting the local charging by the X-ray beam via the photoelectric effect.
These findings suggest a novel approach to control and image domains and domain
walls in multiferroic materials
Applicability of the Debye Waller damping factor for the determination of the line edge roughness of lamellar gratings
Periodic nanostructures are fundamental elements in optical instrumentation
as well as basis structures in integrated electronic circuits. Decreasing sizes
and increasing complexity of nanostructures have made roughness a limiting
parameter to the performance. Grazing-incidence small-angle X-ray scattering is
a characterization method that is sensitive to three-dimensional structures and
their imperfections. To quantify line-edge roughness, a Debye-Waller factor
(DWF), which is derived for binary gratings, is usually used. In this work, we
systematically analyze the effect of roughness on the diffracted intensities.
Two different limits to applying the DWF are found depending on whether or not
the roughness is normally distributed
Scatterometry reference standards to improve tool matching and traceability in lithographical nanomanufacturing
High quality scatterometry standard samples have been developed to improve the tool matching between different scatterometry methods and tools as well as with high resolution microscopic methods such as scanning electron microscopy or atomic force microscopy and to support traceable and absolute scatterometric critical dimension metrology in lithographic nanomanufacturing. First samples based on one dimensional Si or on Si 3 N 4 grating targets have been manufactured and characterized for this purpose. The etched gratings have periods down to 50 nm and contain areas of reduced density to enable AFM measurements for comparison. Each sample contains additionally at least one large area scatterometry target suitable for grazing incidence small angle X ray scattering. We present the current design and the characterization of structure details and the grating quality based on AFM, optical, EUV and X Ray scatterometry as well as spectroscopic ellipsometry measurements. The final traceable calibration of these standards is currently performed by applying and combining different scatterometric as well as imaging calibration methods. We present first calibration results and discuss the final design and the aimed specifications of the standard samples to face the tough requirements for future technology nodes in lithography
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Sample preparation: a crucial factor for the analytical performance of rationally designed MALDI matrices
Evidence is presented that the performance of
the rationally designed MALDI matrix 4-chloro-α-cyanocinnamic acid (ClCCA) in comparison to its well-established predecessor α-cyano-4-hydroxycinnamic acid (CHCA) is significantly dependent on the sample preparation, such as the choice of the target plate. In this context, it becomes clear that any rational designs of MALDI matrices and their successful employment have to consider a larger set of physicochemical parameters, including sample crystallization and morphology/topology, in addition to parameters of basic (solution and/or gas-phase) chemistry
A semi-analytical approach for the characterization of ordered 3D nano structures using grazing-incidence X-ray fluorescence
Following the recent demonstration of grazing-incidence X-ray fluorescence
(GIXRF) based characterization of the 3D atomic distribution of different
elements and dimensional parameters of periodic nanoscale structures, this work
presents a new computational scheme for the simulation of the angular dependent
fluorescence intensities from such periodic 2D and 3D nanoscale structures. The
computational scheme is based on the dynamical diffraction theory in many-beam
approximation, which allows to derive a semi-analytical solution to the Sherman
equation in a linear-algebraic form. The computational scheme has been used to
analyze recently published GIXRF data measured on 2D Si3N4 lamellar gratings,
as well as on periodically structured 3D Cr nano pillars. Both the dimensional
and structural parameters of these nanostructures have been reconstructed by
fitting numeric simulations to the experimental GIXRF data. Obtained results
show good agreement with nominal parameters used in the manufacturing of the
structures, as well as with reconstructed parameters based on the previously
published finite element method simulations, in case of the Si3N4 grating
Scan Free GEXRF in the Soft X ray Range for the Investigation of Structured Nanosamples
Scan free grazing emission X ray fluorescence spectroscopy GEXRF is an established technique for the investigation of the elemental depth profiles of various samples. Recently it has been applied to investigating structured nanosamples in the tender X ray range. However, lighter elements such as oxygen, nitrogen or carbon cannot be efficiently investigated in this energy range, because of the ineffective excitation. Moreover, common CCD detectors are not able to discriminate between fluorescence lines below 1 keV. Oxygen and nitrogen are important components of insulation and passivation layers, for example, in silicon oxide or silicon nitride. In this work, scan free GEXRF is applied in proof of concept measurements for the investigation of lateral ordered 2D nanostructures in the soft X ray range. The sample investigated is a Si3N4 lamellar grating, which represents 2D periodic nanostructures as used in the semiconductor industry. The emerging two dimensional fluorescence patterns are recorded with a CMOS detector. To this end, energy dispersive spectra are obtained via single photon event evaluation. In this way, spatial and therefore angular information is obtained, while discrimination between different photon energies is enabled. The results are compared to calculations of the sample model performed by a Maxwell solver based on the finite elements method. A first measurement is carried out at the UE56 2 PGM 2 beamline at the BESSY II synchrotron radiation facility to demonstrate the feasibility of the method in the soft X ray range. Furthermore, a laser produced plasma source LPP is utilized to investigate the feasibility of this technique in the laboratory. The results from the BESSY II measurements are in good agreement with the simulations and prove the applicability of scan free GEXRF in the soft X ray range for quality control and process engineering of 2D nanostructures. The LPP results illustrate the chances and challenges concerning a transfer of the methodology to the laborator
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