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1
Content available remote

Monte Carlo Simulation of Partially Ordered Atomic Layers Adsorbed on the Monocristalline Surfaces

100%
Wiatrowski G., Le Bossé J., Lopez J., Rousseau J., Zasada I.
Acta Physica Polonica A
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1993
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vol. 83
|
issue 5
587-596
EN
The calculations of the correlations functions and structure factors are performed by means of the Monte Carlo simulation. The results for O/Ni(001) system are presented and compared with those obtained using self-consistent molecular field approximation and cumulant expansion method. The simulation for more complex system CO/Pt(111) is also performed. The calculations of the topological correlations allow us to find the coverage dependence of the incoherent scattering amplitude which can be experimentally detected.
2
Content available remote

Two-Site Correlations in a Surface Layer Adsorbed on the Crystal

100%
Wojtczak L., Zasada I., Le Bossé J., Lopez J., Rousseau J.
Acta Physica Polonica A
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1991
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vol. 80
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issue 5
631-648
EN
The incohorent scattering of electrons by layer adsorbed at a single crystal surface is determined by the Fourier transform of correlation functions of elements forming this layer. The model of the description of atoms or molecules adsorbed on the surface is formulated by the occupation operators which are represented by the pseudospin operators. The calculations of the correlation functions are performed by means of methods which consider a given pair of elements embedded in the effective field of remaining elements of the system while the interaction between the elements of the pair are taken in its exact form. Two approaches are presented here, i.e. the cumulant average and constant coupling approximations, and the case of binary chemisorption is considered in detail. The problem of the correlation symmetry is also discussed.
3
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White Beam Synchrotron Topographic Characterisation of Silicon Wafers Directly Bonded by Oxide Layer

63%
Wierzchowski W., Wieteska K., Graeff W., Gawlik G., Pawłowska M.
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vol. 96
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issue 2
283-288
EN
Various types of layer structures obtained by direct bonding of oxidised silicon wafers were studied by means of different X-ray topographic methods using white synchrotron beam and the observation of selective etching pattern using scanning electron microscopy and optical microscopy with Nomarski contrast. In the present investigation the particularly important results were obtained with synchrotron section topography, which revealed different defects caused by bonding of thick wafers, in particular the dislocations and microcracks. The different situation was observed in the case of bonding with a very thin layer separated from a silicon substrate by high dose proton implantation. In this case a thin layer accommodated practically all induced strain and the bonded oxidised thick substrate remained defect-free in its inner volume.
4
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Positronium Fraction and Positron Life Time at Ni(110) and Ge(110) Surfaces

63%
Shrivastava S., Gupta V.
Acta Physica Polonica A
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1991
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vol. 79
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issue 6
853-859
EN
The fraction of positronium formation and the positron lifetime at Ni(110) and Ge(110) surfaces, when low-energy positrons incident on them, have been calculated using the rate equations approach and positron trapping in image potential well. The calculated results are compared with the available experimental results. The positronium fraction is overestimated at high temperatures in case of Ni(110).
5
Content available remote

Treatment of the Periodically Inhomogeneous Surface: Multiple Boundary Condition

63%
Puszkarski H., Krawczyk M.
Acta Physica Polonica A
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2000
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vol. 97
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issue 6
1017-1022
EN
We deal with the following question: how can the composite nature of a boundary condition formulated for a periodically inhomogeneous surface and involving the composite surface parameter, be treated analytically? We show that when the appropriate Fourier transformation is applied, the composite boundary condition reduces to a specific eigenproblem condition, which constitutes the spectrum of eigenvalues of an "effective" surface parameter, a novel quantity we introduced to account for the nonhomogeneity of the surface.
6
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Very Thin Silver Layer Growth on the Cu(1II) Face at Different Temperatures

63%
Mróz S., Stachnik B.
Acta Physica Polonica A
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1992
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vol. 81
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issue 2
233-238
EN
Measurements of work function changes (ΔΦ) and Auger Electron Spectroscopy were used for investigation of very thin silver layer adsorption on the (111) face of copper crystal. At room temperature the layer-by-layer growth was observed while at temperatures above 850 K ΔΦ and the Auger peak height kinetics indicated the presence of silver diffusion to the surface layer of the copper sample.
7
Publication available in full text mode
Content available

NMR on Surfaces: Present Achievements and Future Prospects

63%
Fick D.
Acta Physica Polonica A
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2001
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vol. 100
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issue 5
615-627
EN
β-NMR experiments with hyperpolarized ^8Li adsorbed on semiconductor and metal surfaces are described (adsorption on Si(111)-(7×7), Si(111)-H, Si(111)-(1×1):H, Ru(001)). They yield detailed information on the electronic properties of these adsorbate-surface systems. Briefly a scenario using hyperpolarized Xe isotopes is sketched, which will extend the potential of the use of hyperpolarized species in NMR experiments on surfaces.
8
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Comparison of Processes Occurring during Silver Adsorption on Copper and Nickel at Elevated Temperatures

63%
Wodecki J., Mróz S.
Acta Physica Polonica A
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1996
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vol. 89
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issue 1
69-74
EN
A flux of silver atoms reevaporated from the copper and nickel targets during deposition of silver was measured as a function of the target temperature during spontaneous cooling from 1150 K and during heating the target with deposited several silver monolayers from room temperature to 1150 K. Differences in the measured dependences for both targets give the evidence of competition between reevaporation of silver atoms from the copper surface and their dissolution in the copper bulk and are in accordance with the lack of silver dissolution in nickel. Thus, the role of silver dissolution in the copper surface layer during silver adsorption at elevated temperatures is experimentally evidenced. Activation energy for silver dissolution in the copper substrate was estimated to be equal to 1.7-2.4 eV/atom.
9
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Content available

Oxygen Emissions from Single-Crystalline Fe_3O_4 Surfaces Induced by Low-Energy Ion Bombardments

63%
Kim-Ngan N., Soszka W.
Acta Physica Polonica A
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2006
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vol. 109
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issue 6
715-721
EN
Negative-charged ion energy spectra of the Fe_3O_4 (001) and (111) surface revealed large peaks attributed to the O^- recoils from a binary collision. Under Ar^+ ion bombardments such an emission was largely affected by the screening effect of the Fe ions. A distinguished peak related to the O^+ recoil ions was observed under Ne^+ ion bombardments, while such a peak was merged into the high background in the case of Ar^+ ion ones. A weak effect from the Verwey transition was found on oxygen emissions. For the (111) surface a small peak characteristic of the O^+ recoils from double collisions appeared in the energy spectra around 140-170 K and a minimum was observed in both R^+(T) and R^-(T) curves under 6 keV Ne^+ ion beam.
10
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Physique des Solides et Morphologie des Surfaces

63%
Rousseau J., Mathia T. G.
Acta Physica Polonica A
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1993
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vol. 83
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issue 5
535-550
EN
PHYSICS OF SOLIDS AND MORPHOLOGY OF SURFACES: The morphology of surfaces is now an important field of research because of its direct connection with the industrial activity like manufacturing and optimising of functional criteria through complicated interfacial phenomena. Presently, characterization of the surface morphology, via the profile metrology, is well modelled by a statistical description. The use of shape morphological parameters allows to identify features of the surface structures generated by the process techniques and the emergence of the different phases of the condensed matter. Starting from the solid state background knowledge, prediction of the surface morphology appears as a tedious way. However, progress in the science of the solids formation and industrial requirements promises the best future for the physicists in such a new technological activity. Philosophy and basic formalism of that approach is presented here.
11
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Studies of Composition of Surfaces and Interfaces with the Use of Auger Electron Spectroscopy

63%
Mróz S.
Acta Physica Polonica A
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1996
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vol. 89
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issue 2
183-193
EN
Processes leading to the Auger electron emission from the sample bombarded with a primary electron beam are discussed. It is shown that every element has its characteristic spectrum of Auger lines, and that owing to a small inelastic mean free path of Auger electrons, information obtained from Auger electron spectroscopy concerns the composition of surface layer of 0.5-1 nm thick. Experimental methods of Auger electron spectroscopy are presented together with problems connected with separation of Auger electrons from the secondary electron spectrum. Advantages and disadvantages of some electron energy spectrometers are considered. Methods of quantitative Auger analysis of homogeneous samples with the use of standards and catalogues of Auger spectra are presented. The role of matrix corrections in quantitative Auger analysis is discussed. Problems arising in Auger analysis of insulating samples are considered and methods of discharging of such samples are presented. Depth profiling of inhomogeneous samples by Auger electron spectroscopy with ion bombardment sputtering is described, and possibilities and limitations of this procedure are discussed. Principles of scanning Auger microscopy are presented. Factors determining the lateral resolution are discussed. Possibilities of Auger electron spectroscopy and scanning Auger microscopy in analysis of composition of grain boundaries exposed by in situ fracture are presented and discussed. Possibilities and limitations of Auger electron spectroscopy in the investigation of solid state surfaces are summarized.
12
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Structural and Magnetic Properties of Co Thin Films on Au(111) Substrates

63%
Walczak A., Ślusarski T., Lehmann-Szweykowska A., Kamieniarz G.
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EN
The structural and magnetic properties of thin Co films grown on Au(111) substrates are investigated using ab initio local-spin-density calculations in the generalized gradient approximation. It is shown that a large lattice intermismatch between Co and Au(111) leads to a strong contraction of the interlayer distances within the Co layer, which adopts either the hexagonal close-packed (α-phase) or the face-centered cubic (β-phase) structure of bulk Co. Magnetic moments in the Co layer are increased beyond their value in bulk Co, the enhancement being strongest at the free surface and at the Co/Au interface, and more modest in the central part of the adlayer. Moderating influence of capping Ag layers on the structure and the magnetic properties of the films has also been considered. It is shown that Ag capping reduces the magnetic moments in comparison to uncovered Co/Au systems.
13
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Nanostructuring and Hardness Investigations of Thin Films by Scanning Force Microscopy

63%
Nowicki M., Richter A., Ries R., Oszwałdowski M.
Acta Physica Polonica A
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1998
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vol. 93
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issue 2
437-441
EN
The scanning force microscope was used to scratch thin films and to write nanoscale pattern on surfaces as well as to perform nanoindentation for hardness measurements. Different thin film materials such as C_{60} films, diamond-like carbon, metals and semiconducting films have been investigated.
14
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Progress into Understanding of Alkali Metal Interaction with a Silicon Surface

51%
Soukiassian P.
Acta Physica Polonica A
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1992
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vol. 81
|
issue 1
19-32
EN
The atomic and electronic structure and interface formation of alkali metal (Na, K, Rb, Cs) and Si(100)2 × 1 surfaces is investigated by photoemission - XPS, UPS - using synchrotron radiation, scanning tunneling microscopy (STM) and by photoemission extended X-ray absorption fine structure (PEXAFS) experiments. The XPS-UPS results indicate that the alkali metal-silicon bond is a weak and polarized covalent bonding even at low coverages with adsorbate metallization at the monolayer. In contrast to III-V semiconductor surfaces, alkali metals do not induce significant structural changes of the surface: STM images performed with atomic resolution for the representative K/Si(100)2×1 systems demonstrate that, at one mono-layer coverage, the K atoms form one-dimensional linear metallic chains parallel to the Si dimers rows ⟨110⟩ direction and distant by 7.68 Å with a single site of adsorption. Below half a monolayer, the K atoms occupy various coexisting sites with no long range order. An ordering transition occurs around half a monolayer in which the adsorbate-adsorbate interaction, which was so far neglected in theoretical calculations, appears to be the leading driving force. The proposed models and concepts are discussed and compared to the latest state-of-art theoretical calculations.
15
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Morphology and Stability of the Diamond/BN (001) and (111) Interfaces Based on Ab Initio Studies

51%
Sznajder M., Hrushka N., Majewski J.
Acta Physica Polonica A
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2016
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vol. 130
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issue 5
1220-1223
EN
The morphology, charge distribution and energetic stability of interfaces in the diamond/c-BN heteropolar junctions grown along [001] and [111] crystallographic directions are obtained from first principles calculations in the framework of density functional theory. It turns out that there exist reconstructions of the abrupt interfaces of the C and N adjacent layers (C-N type) that induce charge compensation and lead to the stabilization of the interfaces. On the contrary, our studies strongly suggest that analogous reconstructions of the abrupt interfaces of C and B adjacent layers (C-B type) are not energetically favorable and do not stabilize abrupt interfaces.
16
Content available remote

Lattice Parameter Relaxation during MBE of ZnTe/Cd_{1-x}Zn_{x}Te/Cd_{0.5}Zn_{0.5}Te Buffer Layers by RHLED and HRTEM

51%
Kret S., Karczewski G., Zakrzewski A., Dłużewski P., Dubon A., Wojtowicz T., Kossut J., Delamarre C., Laval J. Y.
Acta Physica Polonica A
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1995
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vol. 88
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issue 4
795-798
EN
The dynamics of the lattice relaxation processes were investigated us­ing a reflection of a high energy electron diffraction analysis system dur­ing growth by molecular beam epitaxy of ZnTe/Cd_{1-x}Ζn_{x}Te/Cd_{0.5}Mn_{0.5}Te buffers on GaAs substrates. The variation of the lattice parameter recorded by the high energy electron diffraction during the growth was later confirmed by an analysis of high resolution transmission electron microscopy images. We report also on an observation of oscillations of the lattice parameter during the deposition of several first layers of ZnTe on CdTe.
17
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Computer Modeling of Point Defects, Impurity Self-Ordering Effects and Surfaces in Advanced Perovskite Ferroelectrics

51%
Borstel G., Kotomin E. A., Eglitis R. I., Heifets E.
Acta Physica Polonica A
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2000
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vol. 98
|
issue 5
469-481
EN
The calculated optical properties of basic point defects - F-type centers and hole polarons - in KNbO_{3} perovskite crystals are used for the interpretation of available experimental data. The results of quantum chemical calculations for perovskite KNb_{x}Ta_{1-x}O_{3} solid solutions are presented for x=0, 0.125, 0.25, 0.75, and 1. An analysis of the optimized atomic and electronic structure clearly demonstrates that several nearest Nb atoms substituting for Ta in KTaO_{3} - unlike Ta impurities in KNbO_{3} - reveal a self-ordering effect, which probably triggers the ferroelectricity observed in KNb_{x}Ta_{1-x}O_{3}. Lastly, the (110) surface relaxations are calculated for SrTiO_{3} and BaTiO_{3} perovskites. The positions of atoms in 16 near-surface layers placed atop a slab of rigid ions are optimized using the classical shell model. Strong surface rumpling and surface-induced dipole moments perpendicular to the surface are predicted for both the O-terminated and Ti-terminated surfaces.
18
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X-Ray Standing Waves: a Powerful Tool for Interface Studies

51%
Lagomarsino S., Scarinci F., Castrucci P., Giannini C.
Acta Physica Polonica A
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1994
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vol. 86
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issue 4
553-566
EN
The X-ray standing wave technique has demonstrated in these last years to be a powerful method in the study of interfaces. In this paper the fundamentals of the technique will be given, together with examples of applications in the field of metal-semiconductor, of buried semiconductor-semiconductor interfaces and in structural studies of Langmuir-Blodgett films.
19
Content available remote

The Transmission of the Electron Analyzers Determined by Elastic Peak Electron Spectroscopy

51%
Gruzza B., Bondot P., Porte A., Jardin C., Gergely G.
Acta Physica Polonica A
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1992
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vol. 81
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issue 1
159-164
EN
Using the elastic peak electron spectroscopy (EPES), the transmission functions were determined for the 4-grid retarding field and the hemispherical analyzers, which are commonly used for surface physics experiments.
20
Publication available in full text mode
Content available

STM/STS Studies of Self-Organized Growth of Iron Silicide Nanocrystals on Vicinal Si(111) Surface

51%
Wawro A., Suto S., Czajka R., Kasuya A.
Acta Physica Polonica A
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2003
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vol. 104
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issue 3-4
303-319
EN
The evolution of iron silicide structure grown by solid state epitaxy on Si(111) vicinal surface was investigated by scanning tunnelling microscopy. The reactions, which occur on the surface, are compared for two various Fe coverages: 0.33 and 2 monolayers. The annealing at 250˚C does not enable substantial recovery of the surface ordering, deteriorated by Fe deposition at room temperature. The onset of 2×2 surface reconstruction is observed upon annealing at 400˚C. A three-dimensional growth tendency of iron silicide crystallites on a bare Si(111) 7×7 surface was found at 700˚C. In the case of 2 monolayer coverage crystallites nucleate along the edges of substrate terraces forming a regular array of nanometer size dots. Basing on atomically resolved spectroscopic effects and statistical considerations, structure of iron silicide nanocrystallites as well as Schottky-like character of the barrier at the interface between metallic crystallite and semiconducting substrate is deduced.
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