1,720,989 research outputs found
EMRS Spring Meeting 2017, Symposium T: Synthesis, processing and characterization of nanoscale multi functional oxide films VI held May 22-26, 2017, Strasbourg, France
No full textDiffraction analysis of a disordered surface, modelled on a probability distribution of reconstructed blocks: Bi/Si(001)-(2xn), n = 6.45
No full textBismuth adsorbs on the Si(001)-(1 x 2) surface in the form of rows of
dimers. Missing-dimer lines (MDLs) are created perpendicularly every n
units, leading to (2 x n) periodicity. Depending on the coverage, n can
vary from 12 to 5. We investigated by grazing incidence x-ray
diffraction the (2 x n) structure, with n = 6.45. The disorder in the
MDL periodicity, as well as the defects along the MDL, reduce
considerably the correlation length of the reconstructed domains. As a
consequence, the integrated intensity of each reflection must be
corrected, evaluating the trace of the resolution function across the
diffraction node. The structural refinement, based on the as-derived
intensities, provides the Bi dimer bond length (3.11 Angstrom) the Si
atom positions (bulklike), and the height of the Pi plane with respect
to Si (1.88 Angstrom). In addition, we give evidence that the dimers are
displaced along the row from ideal positions towards the MDL (from 0.15
to 0.50 Angstrom). Last, the diffraction profiles are calculated, on the
basis of a probability distribution of (2 x n) cells (n = 6, 7, 1),
using the phase-matrix method. The average positions of the fractional
peaks are related to the concentration of each type of cell. The width
and the intensity of the second order peaks, compared to those of the
first order peaks, allow us to account for the aggregation tendency
EPITAXIAL CONTINUED-LAYER STRUCTURE OF SB ON GAAS(110) AS OBSERVED BY GRAZING-INCIDENCE X-RAY-DIFFRACTION
No full text(1x2) Bi chain reconstruction on the InAs(110) surface
No full textThe atomic geometry of the (Formula presented) Bi reconstruction on the InAs(110) surface has been fully determined by means of grazing incidence x-ray diffraction. The (Formula presented) Bi phase is characterized by couples of unequivalent Bi chains bonded alternatively to In and As atoms. The chains are strongly buckled with respect to the (110) InAs plane and they can easily accommodate if the InAs(110) substrate presents alternate missing rows in the [1-10] direction
STRUCTURAL-ANALYSIS OF THE (1X1)-BI/GAAS(110) INTERFACE
No full textA structural investigation of the (1X1)-Bi/GaAs(110) interface by grazing-incidence x-ray diffraction is presented. The (1X1) structure has been prepared by depositing 1 ML of bismuth at room temperature on a GaAs(110) substrate grown by molecular-beam epitaxy. The structural model for the (1X1) symmetry chemisorption of Bi and the in-plane structural parameters are obtained and compared with previous experimental results. We find that the epitaxial geometry corresponds to a shifted epitaxial continued layer structure (ECLS), contrary to the almost perfect ECLS geometry of the Sb/GaAs(110) interface. We determine a 2.85-Angstrom Bi-Bi bonding length, lower than the bulk Bi value of 3.1 Angstrom, and consistent with the presence of a compression of the Bi atoms within the overlayer
Epitaxial continued layer structure of Sb on GaAs(110) as observed by grazing incidence X ray diffraction
No full textHYDROGEN-INDUCED DERELAXATION ON A MBE GROWN GAAS(110) SURFACE
No full textUp to now only indirect evidences of hydrogen induced derelaxation of the GaAs(110) surface have been obtained. In order to gain direct information on the surface structure MBE prepared GaAs(110) surfaces have been studied after H chemisorption (approximately 1 monolayer) by means of grazing incidence X-ray diffraction (GIXD). Because of the weak interaction of X-rays with H the effect of the hydrogenation can only be addressed through the modifications induced in the GaAs outermost layer. In the absence of surface reconstruction, the information on the in-plane displacements of the Ga and As surface atoms has been derived from integer order peaks at DELTAq(z) almost-equal-to 0. Assuming a constant bond length between surface and bulk atoms, an estimate of the normal atomic coordinates could also be obtained. The main result is a change in the surface structure after hydrogen chemisorption corresponding to a derelaxation of the hydrogenated GaAs(110) surface
HYDROGEN-INDUCED DERELAXATION ON A MBE GROWN GAAS(110) SURFACE
No full textUp to now only indirect evidences of hydrogen induced derelaxation of the GaAs(110) surface have been obtained. In order to gain direct information on the surface structure MBE prepared GaAs(110) surfaces have been studied after H chemisorption (approximately 1 monolayer) by means of grazing incidence X-ray diffraction (GIXD). Because of the weak interaction of X-rays with H the effect of the hydrogenation can only be addressed through the modifications induced in the GaAs outermost layer. In the absence of surface reconstruction, the information on the in-plane displacements of the Ga and As surface atoms has been derived from integer order peaks at DELTAq(z) almost-equal-to 0. Assuming a constant bond length between surface and bulk atoms, an estimate of the normal atomic coordinates could also be obtained. The main result is a change in the surface structure after hydrogen chemisorption corresponding to a derelaxation of the hydrogenated GaAs(110) surface
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