1,721,095 research outputs found
X-Ray Microanalysis Combined with Monte Carlo Simulation for the Analysis of Layered Thin Films: The Case of Carbon Contamination
No full textA previously developed Monte Carlo code has been extended to the X-ray microanalysis in a (scanning) transmission electron microscope of plan sections, consisting of bilayers and triple layers. To test the validity of this method for quantification purposes, a commercially available NiOx thin film, deposited
on a carbon layer, has been chosen. The composition and thickness of the NiO film and the thickness of the C support layer are obtained by fitting to the three X-ray intensity ratios I (NiK)/I(OKI)/I(NiK!/I (CK), and I (OK)/I(CK).Moreover, it has been investigated to what extent the resulting film composition is affected by the
presence of a contaminating carbon film at the sample surface. To this end, the sample has been analyzed both in the (recommended) “grid downward” geometry and in the upside/down (“grid upward”) situation. It is found that a carbon contaminating film of few tens of nanometers must be assumed in both cases, in addition to the C support film. Consequently, assuming the proper C/NiOx /C stack in the simulations, the Monte Carlo method yields the correct oxygen concentration and thickness of the NiOx film
Application of the parametric bootstrap method to determine statistical errors in quantitative X-ray microanalysis of thin films
No full textWe applied the parametric bootstrap to the X-ray microanalysis of
Si-Ge binary alloys, in order to assess the dependence of the Ge
concentrations and the local film thickness, obtained by using
previously described Monte Carlo methods, on the precision of the
measured intensities. We show how it is possible by this method
to determine the statistical errors associated with the
quantitative analysis performed in sample regions of different
composition and thickness, but by doing only one measurement. We
recommend the use of the bootstrap for a broad range of applications for
quantitative microanalysis to estimate the precision of the final
results and to compare the performances of different methods to
each other. Finally, we exploited a test based on bootstrap
confidence intervals to ascertain if, for given X-ray intensities,
different values of the estimated composition in two points of the
sample are indicative of an actual lack of homogeneity
Quantitative thin film X-ray microanalysis by STEM/HAADF: Statistical analysis for precision and accuracy determination.
No full textSilicon-germanium thin films have been analysed by EDS
microanalysis in a FEG-STEM equip-ped with a high angular
dark-field detector (STEM/HAADF). Several spectra have been
acquired in the same homogeneous area of the cross-sectioned
sample by drift-corrected linescan acquisitions. The Ge
concentrations and the local film thickness have been obtained by
using a previously described Monte-Carlo based `2 tilt-angle'
method. While the concentrations are in excellent agreement with
the known values, the resulting confidence intervals are not as
good as expected from the precision in beam positioning and tilt
angle position and read out offered by our state-of-the-art
microscope. The Gaussian shape of the SiK_alpha and GeK_alpha X-ray intensities allows one to use the parametric bootstrap method of statistics, whereby it becomes possible to perform the same quantitative analysis in sample regions of different composition and thickness, but by doing only one measurement at the two angles
Electron diffraction with ten nanometer beam size for strain analysis of nanodevices
No full textA method to perform nanobeam diffraction (NBD) in a transmission electron microscope with high spatial resolution and low convergence angle is proposed. It is based on the use of a properly fabricated condenser aperture of 1 mu m in diameter, which allows an electron beam about 10 nm in size to be focused on the sample, with a convergence angle in the 0.1 mrad range. Examples of NBD patterns taken in an untilted cross section of a silicon device are shown. Their quality is adequate for spot position determination and hence to obtain, in principle, quantitative strain information. (C) 2008 American Institute of Physics. {[}DOI: 10.1063/1.3003581]
Magnetic measurements and TEM investigations on Fe-Co ultrafine powders derived from a bimetallic carbonyl cluster
No full textThe molecular carbonyl cluster HFeCo3(CO)12(1) affords an ultrafine Fe–Co powder by thermal treatment under inert atmosphere. Several magnetic or magneto–structural transformations have been evidenced by thermomagnetic analysis (TMA) from 20 to 950 °C. Transmission electron microscopy (TEM) investigations on samples treated at an intermediate temperature showed the presence of both mono- and bi-metallic crystallites of nanometric size. The saturation magnetization was found to increase with increasing annealing temperature, while the opposite behaviour was found for coercitivity. A comparison was made with the magnetic properties of the cast FeCo3 alloy
Strain field reconstruction in shallow trench isolation structures by CBED and LACBED
No full textUsing a combination of the CBED and the LACBED techniques in the transmission electron microscopy (TEM), we have investigated the strain field in the silicon active region of a shallow trench isolation structure, underlying a TiSi2 layer. Starting from the analysis of the deformation in a sample, thinned for TEM analysis, we have reconstructed the displacement field, simulating the split HOLZ lines visible in the experimental CBED patterns. From the comparison between the experimental LACBED patterns, taken in a suitable sample orientation to evidence the stressors distribution in the polycrystalline silicide layer, and the corresponding dynamically simulated ones, we have reproduced the strain field in the unthinned, bulk sample. (c) 2006 Elsevier B.V. All rights reserved
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