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1
Content available remote

Electronic Structure of Diluted Semimagnetic Semiconductor (Cd,Co)Se

100%
Cháb V., Mašek J., Orłowski B., Kowalski B.
Acta Physica Polonica A
|
1991
|
vol. 80
|
issue 3
333-336
EN
The electronic structure of a new semimagnetic semiconductor (Cd,Co)Se is studied by UPS and calculated by a tight-binding version of the disordered-local-moment theory. The theory accounts for the chemical disorder and for electron interactions within the Co 3d^{7} shells. Both theory and experiment show Co 3d states deep in the valence band and also at the band edge. The last state seem to be responsible for unique properties of the Co-based semimagnetic semiconductors.
2
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Reflectivity Study of the Zn_{1-x}Co_{x}Se Crystals

100%
Kowalski B., Gołacki Z., Orłowski B.
Acta Physica Polonica A
|
1991
|
vol. 80
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issue 3
393-396
EN
The room temperature reflectivity spectra of the Zn_{1-x}Co_{x}Se (x = 0, 0.03, 0.05) crystals have been measured in the visible and ultraviolet range from 1.7 to 12 eV. The structure of the spectra was interpreted in terms of the electronic band structure of the binary material (ŻnSe). The experimental results were compared with the reflectivity spectra of the Fe-based semi magnetic semiconductors [1], and the interpretation was confronted with the conclusions derived from the photoemission experiments performed for Cd_{1-x}Co_{x}Se [2] and the tight-binding CPA calculations of the band structure of Zn_{1-x}Co_{x}Se [3].
3
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Reflectivity Study of HgSe_{1-x}Te_{x} Crystals

100%
Kowalski B., Dybko K., Lemańska A., Orłowski B.
Acta Physica Polonica A
|
1992
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vol. 82
|
issue 5
845-848
EN
The room temperature reflectivity spectra of HgSe_{1-x}Te_{x} (x = 0, 0.4, 0.5, 1.0) crystals were measured in the visible and ultraviolet range from 1.5 to 12 eV. The maxima characteristic of the binary HgA^{IV} compounds can be revealed in the mixed crystals spectra, but their position depends on the crystal composition. There is no duplication of the spectral features in spite of the different energy position of the maxima for HgSe and HgTe. This suggests that the virtual crystal approximation could be used to describe basic optical properties of HgSe_{1-x}Te_{x}.
4
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Reflectivity Spectra of Cd_{1-x}Mn_{x}F_{2} in the 5-35 eV Energy Range

100%
Francini R., Zimnal-Starnawska M., Zema N., Orłowski B.
Acta Physica Polonica A
|
1991
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vol. 80
|
issue 3
453-456
EN
The reflectivity spectra of Cd_{1-x}Mn_{x}F_{2} crystals, in the 5-35 eV energy range at 300 and 77 K, were investigated. The observed changes in the shape of spectra, caused by increase of the Mn content, are compared with the calculated band structure of pure CdF_{2} and with the already available results of XPS experiments for these crystals. The increasing concentration of Mn results in the blurring of the reflectivity structures and shifts the energy of direct exciton (as compared to pure CdF_{2}). Qualitative arguments (hybridization of Mn^{2+} 3d and F^{-} 2p states) can describe these effects but a quantitative explanation would require a detailed band structure calculation for these compounds.
5
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Resonant Photoemission Study οf 4f Electrons on the Surface οf Semiconductors

100%
Orłowski B., Kowalski B., Pietrzyk M., Buczko R.
Acta Physica Polonica A
|
2008
|
vol. 114
|
issue S
S-103-S-114
EN
The contribution of 4f electrons to the electronic structure of the semiconductor clean surface caused by the surface doping of it by rare-earth metal atoms (Eu, Sm) will be presented. The surface doping was performed by the controlled, sequential deposition of the rare-earth metal atoms on the clean surface in UHV conditions (Sm on GaN or CdTe) or by the doping of the layer volume of (EuGd)Te. After each deposition or surface treatment the synchrotron radiation was used to measure in situ the resonant photoemission spectra (the Fano type resonance) to study the contribution of 4f electrons of divalent and trivalent Sm and Eu ions to the valence band electronic structure of created sample. The first stages of the metal atoms deposition lead to the surface doping. Further metal atoms deposition leads to the growth of the metallic islands on the surface and causes the appearance of the sharp metallic Fermi edge in the energy distribution curves. Proper coverage and annealing of the sample surface with metal atoms leads to the diffusion of the metal atoms into the sample and results in an increase in the crystal doping and decrease in the metallic islands contribution to the measured spectra. As a result, the new electronic structure of the valence band can be created and investigated in situ.
6
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Analysis of 4f Level in Samarium-Rich MBE Grown CdSmTe Sample

88%
Szamota-Sadowska K., Gołacki Z., Orłowski B., Boyn R., Johnson R.
Acta Physica Polonica A
|
1998
|
vol. 94
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issue 3
560-564
EN
Electronic states of 4f samarium ions were investigated by photoemission spectroscopy in samarium-rich CdSmTe sample obtained by MBE. The photon energy of synchrotron radiation allowed to investigate Fano-type resonance and antiresonance. The energy distribution curve spectra were attributed to the Sm 4d-4f transition. The shape of the constant initial states spectra was compared with this one obtained for atomic samarium.
7
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Contribution of Mn 3d Electrons To the Valence Band of Sn_{0.9}Mn_{0.1}te

88%
Nadolny A., Guziewicz E., Kowalski B., Orłowski B., Johnson R.
Acta Physica Polonica A
|
1998
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vol. 94
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issue 3
454-458
EN
The synchrotron radiation in the energy range between 15 and 70 eV was used to investigate the electronic structure of the crystalline Sn_{0.9}Mn_{0.1}Te by means of the resonant photoemission spectroscopy. Fano-type resonance has been observed in the obtained constant initial energy curves with the resonant energy 50.6 eV and antiresonant energy 49.0 eV. The energy distribution curves taken at photon energies close to the Mn 3p-3d transitions allow us to conclude that Mn atoms contribute to the valence band mainly at energies of 4.0 eV and 7.8 eV below the valence band edge.
8
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Angle-Resolved Photoelectron Spectroscopy on CdTe(100) c(2×2)

76%
Gawlik K., Brügmann J., Harm S., Manzke R., Skibowski M., Kowalski B., Orłowski B.
Acta Physica Polonica A
|
1993
|
vol. 84
|
issue 6
1093-1099
EN
The CdTe(100) c(2×2) surface prepared by ion bombardment and annealing was investigated by angle-resolved photoemission spectroscopy using synchrotron radiation with photon energies between 8.5 eV and 32 eV. The bulk band structure was determined along the ΓΔX-direction normal to the surface measuring energy-distribution curves. The results are compared with a theoretical valence band structure assuming free-electron-like final states in connection with k-conservation. For further comparison we calculated the final states by the pseudopotential method and analyzed the results in form of structure plots. In this way, most of the dispersing maxima in the normal emission spectra can be explained. For this mode of photoelectron spectroscopy the resulting dispersion must be due to the component of the Bloch wave vector normal to the surface, k_{⊥}, keeping surface related structures at a fixed binding energy position E_{b}. The lack of dispersion for five structures along ΓΔX gives experimental evidence for their surface origin.
9
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Fe 3d Contribution to Hg_{1-x}Fe_{x}Se Valence Band by Means of Angle-Resolved Photoemission

76%
Orłowski B., Bonnet J., Hricovini C., Pinchaux R., Górecka J., Kowalski B., Mycielski A.
Acta Physica Polonica A
|
1991
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vol. 80
|
issue 3
389-392
EN
The Angle-Resolved Photoemission Electron Spectroscopy (AR PES) was applied to investigate the electronic structure of HgSe and Hg_{1-x}Fe_{x}Se crystals for (110) surface. The measured set of Angle-Resolved Energy Distribution Curves (AR EDCs) permits to determine some of the elements of the electronic band structure E(k) (energy-momentum dependence for ҐKX and ҐX directions in the Brillouin zone) for measured crystals. The Fe 3d contribution gives the states lying over the edge of the valence band of HgSe crystal (0.25 eV), and into the valence band.
10
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Resonant Photoemission Study of Mn 3d Electrons Contribution to the Pb_{0.92}Mn_{0.08}Se Valence Band

76%
Orłowski B., Kowalski B., Le K., Gałązka R., Ghijsen J., Johnson R.
Acta Physica Polonica A
|
1995
|
vol. 87
|
issue 2
329-332
EN
The resonant photoemission spectroscopy was applied to investigate the valence band electronic structure of semimagnetic semiconductor Pb_{0.92}Mn_{0.08}Se crystal and to determine the contribution of Mn 3d electrons to the valence band. The set of energy distribution curves and constant initial states spectra were taken for by energies in the region (40-60 eV) close to the Mn 3p-3d transition. The electrons Mn 3d hybridize and contribute to the valence band electrons of the crystal and main density of states contribution appears in the energy 3.5 ± 0.2 eV below the valence band edge.
11
Content available remote

4f Contribution to Valence Band of Pb_{1-x}RE_{x}S (RE = Eu,Gd) Studied by Resonant Photoemission

76%
Kowalski B., Gołacki Z., Guziewicz E., Orłowski B., Ghijsen J., Johnson R.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 5
1035-1039
EN
Resonant photoemission experiments were carried out in order to reveal the contributions of partly filled Eu 4f^{7} and Gd 4f^{7} shells to the valence bands of Pb_{0.95}Eu_{0.05}S and Pb_{0.95}Gd_{0.05}S crystals. The coupling between these orbitals and the host electronic states is discussed.
12
Content available remote

Electronic Band Structure of Cubic HgS

76%
Guziewicz E., Kowalski B., Orłowski B., Dybko K., Witkowska B., Szuszkiewicz W.
Acta Physica Polonica A
|
1995
|
vol. 87
|
issue 2
395-398
EN
Reflectivity spectra of Hg_{1-x}Fe_{x}S (x < 0.04) and HgSe_{1-y}S_{y} (y < 0.5) mixed crystals were measured in the vacuum ultraviolet energy range from 4 to 12 eV. Information about the electronic band structure of cubic modi­fication of HgS resulting from the above data is analyzed and discussed.
13
Content available remote

Visible Luminescence from Porous Silicon

76%
Bała W., Firszt F., Nossarzewska-Orłowska E., Brzozowski A., Orłowski B., Kowalski B., Guziewicz E.
Acta Physica Polonica A
|
1993
|
vol. 84
|
issue 4
761-764
EN
This paper presents results of investigation of the temperature dependence of visible luminescence in porous silicon layers prepared by anodization in hydrofluoric acid. Luminescence spectra were measured in the temperature range between 40 K and 350 K. Room temperature reflectivity spectra were also measured in vacuum ultraviolet radiation range from 4 eV to 12 eV.
14
Content available remote

Valence Band Density of States and Mn 3d Contribution in Mn_{1-x}Mg_{x}Te

76%
Kowalski B., Guziewicz E., Kopalko K., Orłowski B., Janik E., Wojtowicz T., Johnson R.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 3
401-405
EN
Resonant photoemission spectroscopy was applied to determine the Mn 3d derived contribution to the valence band density of states of Mn_{0.44} Mg_{0.56}Te grown by molecular beam epitaxy on a GaAs(001) substrate. The modifications of the valence band density-of-states distribution are discussed as a consequence of the substitution of Mg ions for Mn ions.
15
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Resonant Photoemission Study of Cd_{1-x}Fe_{x}Se Valence Band

76%
Orłowski B., Fraxedas J., Denecke R., Kowalski B., Mycielski A., Ley L.
Acta Physica Polonica A
|
1991
|
vol. 79
|
issue 2-3
355-358
EN
The phenomenon of Fano type resonant photoemission was used to distinguish the Fe electrons derived partial contribution to the valence band of a semimagnetic semiconductor Cd_{1-x}Fe_{x}Se. The states appearing at the middle of the valence band correspond to the Fe 3d electrons while the step of the density of states obtained at the valence band edge region correspondsvto the hybridized s-p-d electrons.
16
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Electronic Structure of the CdTe(100)-(1×1) Surface

64%
Gawlik K., Brugmann J., Harm S., Janowitz C., Manzke R., Skibowski M., Solterbeck C., Schattke W., Orłowski B.
Acta Physica Polonica A
|
1992
|
vol. 82
|
issue 2
355-361
EN
Unreconstructed CdTe(100) surface prepared by ion bombardment and annealing is investigated by angle-resolved photoemission. The experimental band structure E(k_{∥}) is determined along high-symmetry lines of the surface Brillouin zone by measuring energy-distribution curves of photoelectrons. Different criteria were applied to separate surface and bulk related spectral features, e.g. calculating the position of bulk-derived emissions in the frame of the free-electron final state approximation assuming k conservation. In this way, most dispersing features could be explained. All remaining features were compared with theoretical surface band structures for different polar surface terminations which were calculated within a layer doubling procedure on the basis of an EHT-fit to the bulk band structure. The investigated CdTe(100)-(1×1) surface could be identified as Cd terminated. Two surface bands were observed, one located above the valence-band edge and the second in the open pocket of the projected bulk band structure along the Γ̅K̅ direction. At 4.6 eV binding energy an additional weakly dispersing band was found, which contains mixed surface and bulk character. The high density of bulk states associated with this edge of the heteropolar gap is also expected to contribute to this feature.
17
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Content available

The Surface Hydro-Oxidation of LaNiO_{3-x} Thin Films

64%
Mickevičius S., Grebinskij S., Bondarenka V., Lisauskas V., Šliužienė K., Tvardauskas H., Vengalis B., Orłowski B., Osinniy V., Drube W.
Acta Physica Polonica A
|
2007
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vol. 112
|
issue 1
113-120
EN
The high-energy X-ray photoelectron spectroscopy was used to determine the composition and chemical structure of epitaxial LaNiO_{3-x} films obtained by a reactive dc magnetron sputtering. It was found that the oxide and hydroxide species of La and Ni are on the films surface. The thickness of hydroxide enriched layer, estimated from the oxide and hydroxide peak intensities, is about 2 nm.
18
Content available remote

Photoemission Study of Mn 3d Electrons in the Valence Band of Mn/GeMnTe

64%
Pietrzyk M., Kowalski B., Orłowski B., Knoff W., Osinniy V., Kowalik I., Story T., Johnson R.
Acta Physica Polonica A
|
2007
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vol. 112
|
issue 2
275-281
EN
We present the results of the electronic band structure study of Ge_{0.9}Mn_{0.1}Te epilayers, clean and modified in situ by deposition of manganese atoms. The sets of resonant photoemission spectra were measured for the photon energy range covering the energy of Mn 3p→3d transition (45
19
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Cd_{1-x}Fe_{x}Se/Fe Interface Formation Observed by Means of Photoemission Spectroscopy

64%
Guziewicz E., Orłowski B., Kowalski B., Barrett N., Martinotti D., Guillot C., Lacharme J., Sebenne C.
|
EN
We present a new outlook at the study of metal-semiconductor interface formation. A resonant photoemission spectroscopy tuned to the Fe 3p-3d transition (56 eV) was used to investigate the changes after sequential deposition of Fe atoms on freshly cleaved Cd_{0.86}Fe_{0.14}Se crystal surface. In the first stages (0.6-4 ML) of Fe deposition the contribution of Fe 3d electrons to the valence band grows up markedly indicating the increase in Fe content in the Cd_{0.86}Fe_{0.14}Se crystal surface region. When the amount of Fe exceed 40 ML the resonant photoemission spectra became similar to the Fe metal with some contribution of the ternary crystal substrate.
20
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Influence of Yb on Valence Band Density of States of CdYbTe and PbYbTe - a Resonant Photoemission Study

52%
Szamota-Sadowska K., Kowalski B., Guziewicz E., Orłowski B., Sadowski J., Gołacki Z., Ghijsen J., Johnson R., Belkhou R., Radosavkič D., Martinotti D., Barrett N., Guillot C.
Acta Physica Polonica A
|
1996
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vol. 90
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issue 5
943-946
EN
Photoemission measurements using synchrotron radiation were performed on PbYbTe (bulk crystal) and CdYbTe (MBE thin film). The resonant enhancement of the photoemission was applied for investigation of the contribution of Yb 4f electrons to the valence band. The set of the energy distribution curves was collected for energies in the region close to the 4d-4f Fano transition. The Yb 4f^{14} were observed at the binding energies close to the edge of the valence band while the 4f^{13} states were revealed deep in the valence band.
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