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1
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III-V Semiconducting Nitrides Energy Gap under Pressure

100%
Perlin P., Gorczyca I., Teisseyre H., Suski T., Litwin-Staszewska E., Porowski S., Grzegory I., Christensen N.
Acta Physica Polonica A
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1992
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vol. 82
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issue 4
674-676
EN
In this paper we present overview of our recent experimental and theoretical results concerning electronic band structure of III-V nitrides under pressure. It is shown here that the pressure coefficients of the direct gap for studied nitrides are surprisingly small. To describe tendency in changes of the gap with pressure we use a simple empirical relation.
2
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Surface Photovoltage Spectroscopy of Cd_{0.97}Fe_{0.03}Se and Cd_{0.97}Fe_{0.03}Te Crystals

100%
Sarem A., Οrlowski B. A., Kuźmiński S.
Acta Physica Polonica A
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1991
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vol. 79
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issue 2-3
183-186
EN
The surface electronic structure of the Cd_{1-x}Fe_{x}Se and Cd_{1-x}Fe_{x}Τe crystals with x = 0 and x = 0.03 has been studied by Surface Photovoltage Spectroscopy (SPS). The change of surface photovoltage was observed due to photo-excitation of the electrons from the deep donor state Fe 3d to conduction band edge. This gave possibility to determine energy position of the Fe 3d state at 0.64 and 0.15 eV over the top of the valence band for CdSe and CdTe, respectively.
3
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Peculiarities of Composition and Temperature Dependence of Energy-Band Parameters of Zn_{x}Cd_{y}Hg_{1-x-y}Te

100%
Andrukhiv A. M., Ivanov-Omskii V. I., Polit J., Sheregii E. M.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
513-517
EN
The influence of addition of Zn on band parameters of Zn_{x}Cd_{y}Hg_{1-x-y}Te solid solution at different temperatures (4.2-200 K) was investigated. The cyclotron resonance at 4.2 K and magnetophonon reso­nance at 77-200 K were used to determine band structure parameters. The temperature dependence of band structure parameters (energy gap, effec­tive mass of electron) for the composition of series of epilayers (x varied in 0.08-0.20 range and y - 0.07-0.12) was obtained. It is found that band struc­ture parameters for some compositions (for example x = 0.17, y = 0.08) are almost independent from temperature and equal: γ₁^{L}= 19.55, γ₂^{L} = γ₃^{L} = 8.5, K^{L} = 6.48, F = -0.5, E_{g} = 0.35 eV, E_{p} = 17.9 eV. The effective mass of electrons was found to be greater with addition of Zn while the effective mass of heavy holes is left unchanged.
4
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Temperature and Composition Dependence of Photovoltaic Spectra of Pb_{1-x}Mn_{x}Se Diodes

100%
Le-Van-Khoi, Szczerbakow A., Karczewski G., Gałązka R. R.
Acta Physica Polonica A
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1991
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vol. 79
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issue 2-3
287-290
EN
Photovoltaic spectra of Pb_{1-x}Mn_{x}Se homojunctions have been measured in the infrared spectral region within the temperature range 15-300 K. The junctions have been formed by cadmium diffusion into the p-type Pb_{1-x}Mn_{x}Se crystals with manganese content 0 ≤ x ≤ 0.08. From the positions of the photovoltaic maxima the energy band gap of the diode material has been determined. A phenomenological expression describing the energy band gap of Pb_{1-x}Mn_{x}Se as a function of temperature and crystal composition has been proposed. In diodes containing high manganese content x = 0.06 and x = 0.08 a second photovoltaic maximum caused by indirect optical transitions between the main conduction band and the secondary valence band located along the ∑-axis of the Brillouin zone has been observed.
5
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Band Structure and Refractive Index of Gallium Nitride Under Pressure

63%
Perlin P., Gorczyca I., Suski T., Teisseyre H., Grzegory I., Christensen N.
Acta Physica Polonica A
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1991
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vol. 80
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issue 3
421-424
EN
The effect of hydrostatic pressure on direct gap and refractive index of GaN is investigated up to 5.5 GPa. Band structure of GaN is calculated by Linear Muffin-Tin Orbitals (LMTO) method for different values of pressure. Resulting pressure coefficient of the main gap and of the refractive index are in a good agreement with the experimental ones.
6
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4f Contribution to Valence Band of Pb_{1-x}RE_{x}S (RE = Eu,Gd) Studied by Resonant Photoemission

63%
Kowalski B., Gołacki Z., Guziewicz E., Orłowski B., Ghijsen J., Johnson R.
Acta Physica Polonica A
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1996
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vol. 90
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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.
7
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Influence of Chemistry on the Energy Band Structure: AlAs Versus GaAs

63%
Bogusławski P., Gorczyca I.
Acta Physica Polonica A
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1991
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vol. 80
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issue 3
433-436
EN
Energy band structure of AlAs and GaAs is analyzed in terms of the energy structure of the constituent atoms. Conduction band wave functions are projected on s-, p-, and d-symmetry atomic orbitals. The resulting information is combined with the eigenenergies of Al and Ga atoms, in order to-discuss the character of the band gaps, and the sign of deformation potentials.
8
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ZnS/ZnSe Superlattices under Pressure

63%
Gorczyca I., Christensen N.
Acta Physica Polonica A
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1993
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vol. 84
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issue 4
753-756
EN
Self-consistent linear muffin-tin orbital method is used to calculate the band structure of ZnS/ZnSe (001) strained-layer superlattice and investigate the influence of hydrostatic pressure on the valence band offset (VBO). Three different strain modes corresponding to various values of the relative thicknesses of both materials are considered. A I → II type conversion associated with the conduction-band crossover between the ZnSe well and ZnS barrier layers is found in agreement with recent experimental data.
9
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Extended X-ray Bremsstrahlung Isochromat Fine Structure of SiO_{2}

63%
Sobczak E., Nietubyć R.
Acta Physica Polonica A
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1995
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vol. 87
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issue 3
649-656
EN
X-ray bremsstrahlung isochromat of amorphous SiO_{2} deposited on Si crystal was measured in an energy range up to 250 eV above the threshold. Extended X-ray bremsstrahlung isochromat he structure (EXBIFS) was observed up to 150 eV for SiO_{2} studied. The Fourier transform of EXBIFS showed two peaks originated from first and second neighbors around silicon and oxygen ions. Model calculations of EXBIFS of amorphous SiO_{2} were performed in terms of single scattering of spherical waves and compared with experimental results.
10
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Nonlinear Temperature Dependence of the Band Gap in Hg_{1-x-y}Cd_{x}Mn_{y}Te and Hg_{1-x}Cd_{x}Te Alloys

63%
Dudziak E., Jędral L. Z., Bożym J., Brzeziński J.
Acta Physica Polonica A
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1991
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vol. 79
|
issue 2-3
291-294
EN
The temperature dependence of the band gap for HgCdTe and HgCdMnTe has been experimentally investigated in the temperature range of 7-250 K. The distinct nonlinear dependence has been observed in the low temperature range. It was shown that the lattice dilatation contribution calculated for HgCdTe is a significant part (about 30%) of the total temperature shift of the energy gap.
11
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Photovoltaic Effect on PbTe p-n Junction in the Presence of Magnetic Field

51%
Le K., Grodzicka E., Witkowska B., Story T., Gałązka R.
Acta Physica Polonica A
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1993
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vol. 84
|
issue 4
721-724
EN
Photovoltaic spectra of PbTe p-n junction have been measured in the infrared spectral region in the temperature range of 8-260 K. The p-n junctions have been formed by cadmium diffusion into the p-type PbTe crystals. From the positions of the photovoltaic maxima the energy gap of the diode material has been determined. In the presence of a magnetic field up to 7 T, a pronounced oscillatory behavior of the photovoltage was observed in the Faraday and Voigt configurations. Experiments were performed as a function of the magnetic field intensity at a constant wavelength of the incident light. The energy of the interband magnetooptical transitions between the Landau levels in PbTe was determined and compared with the theoretical model of Adler, describing the energy band structure for the IV-VI compounds.
12
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Magnetooptical Studies of CdTe-Rich Epitaxial Layers

51%
Dudziak E., Bożym J., Pruchnik D., Jędral L.
Acta Physica Polonica A
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1991
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vol. 80
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issue 3
325-328
EN
The first magnetooptical studies comprising magnetoreflection, magnetoabsorption and Faraday rotation of CdTe-rich Hg_{1-x-y}Cd_{x}Mn_{y}Te are reported. The drastic disappearing of excitonic structure, for already very small Hg content, has been observed. The exchange parameters close to those for CdMnTe have been found.
13
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Theoretical Study of Optical and XANES Spectra for CdTe within the k-dependent Matrix Element Approach

51%
Markowski R., Oleszkiewicz J., Kisiel A.
Acta Physica Polonica A
|
1992
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vol. 82
|
issue 5
785-788
EN
The reflectivity and X-ray absorption near-edge structure spectra for CdTe were calculated with the inclusion of the transition matrix elements from band structure obtained within self-consistent, relativistic linear muffin tin orbital method. The results were compared with experimental data for the case of CdTe and with our previous calculations.
14
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Photovoltaic Effect of ZnTe-Cd_{1-x}Mn_{x}Te_{1-y}Se_{y} Heterojunctions in Presence of Magnetic Field

51%
Gałązka R. R., Khoi N. T.
Acta Physica Polonica A
|
1995
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vol. 88
|
issue 5
841-844
EN
Photovoltaic effect of the ZnTe-Cd_{1-x}Mn_{x}Te_{1-y}Se_{y} heterojunctions, prepared by vapor-transport epitaxy of ZnTe on Cd_{1-x}Mn_{x}Te_{1-y}Se_{y} substrate was studied. The photovoltaic measurements were carried out over the temperature range from 12 K to 300 K and in the magnetic field up to 6 T. In the magnetic field, maximum of the sensitivity corresponding to the energy of the forbidden gap of Cd_{1-x}Mn_{x}Te_{1-y}Se_{y} substrate splits into two components for σ^{+} and σ¯ circular polarizations of incident light. This phenomenon was ascribed to the exchange interaction of the magnetic moments of Mn^{++} ions with band electrons. From the value of the splitting energy the exchange integral N_{0}(α-β) was determined to be 1.15 ± 0.2 eV.
15
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Magnetooptical Properties of Pb_{1-x}Mn_{x}Se p-n Junctions

51%
Khoi L., Karczewski G., Dobrowolski W., Kossut J., Gałązka R.
Acta Physica Polonica A
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1991
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vol. 80
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issue 3
445-448
EN
The first experimental evidence of the magnetic quantum oscillation in the photovoltaic effect of Pb_{1-x}Mn_{x}Se p-n junctions is reported. The p-n junctions were obtained in Pb_{1-x}MnxSe crystals with manganese content, 0 ≤ x ≤ 0.08 by introducing Cd donors by diffusion. Measurements were per formed between 5-85 K and in the presence of the magnetic field 0-7 T in the Faraday and Voigt configurations of the incident infrared radiation of various photon energies in the vicinity of the energy gap of a Pb_{1-x}Mn_{x}Se. Strong oscillatory behavior of the photovoltage was observed as a function of the magnetic field intensity at a constant wavelength of the incident light. Using the model of Adler of the energy band structure modified by the exchange terms, and after identification of the initial and final states of the transitions, we derive the band parameters of the Pb_{1-x}Mn_{x}Se crystals.
16
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The Influence of the Dipol Transition Matrix Element on the XANES and Optical Spectra for CdTe

51%
Markowski R., Oleszkiewicz J., Kisiel A.
Acta Physica Polonica A
|
1991
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vol. 80
|
issue 3
369-372
EN
The reflectivity and X-ray absorption near-edge spectra (XANES) for CdTe have been calculated with inclusion of the transition matrix element from band structure obtained from self-consistent linear muffin-tin-orbital (LMTO) method. The result has been compared with experimental data for the case of CdTe.
17
Content available remote

Photoemission and Inverse Photoemission Studies of SiO_{2}

51%
Sobczak A., Nietubyć R., Sobczak J. W.
|
EN
Occupied and unoccupied electron states of amorphous silicon dioxide film supported on Si crystal are studied by using X-ray photoemission and, for the first time, X-ray inverse photoemission (X-ray bremsstrahlung isochromat method). A special care was undertaken to minimize decomposition of silicon oxide during X-ray bremsstrahlung measurements. The experimental spectra are compared with theoretical band structure calculations for amorphous SiO_{2} from the literature and good overall agreement is found.
18
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Self-Induced Persistent Photoconductivity in ZnTe-Cd_{1-x}Mn_{x}Te_{1-y}Se_{y} Heterojunctions

51%
Van Khoi L., Dobrowolski W., Zakrzewski A., Dobaczewski L., Gałązka R.
|
EN
At temperatures lower than 200 K the photomemory effect has been observed in ZnTe-Cd_{1-x}Mn_{x}Te_{1-y}Se_{y} heterojunctions. The persistent photoconductivity can be achieved either by illumination from an external light source or by a self-absorption of the electroluminescence radiation when a voltage of about 10 V for a few seconds is applied to the diode. Current-voltage characteristics are of the form I~ V^{m}. The capacitance and electroluminescence measurements show that the photomemory effect in ZnTe-Cd_{1-x}Mn_{x} Te_{1-y}Se_{y} heterojunctions can be caused by the bistable nature of the In dopant in the Cd_{1-x}Mn_{x}Te_{1-y}Se_{y} substrate. In the high resistivity interface layer and the substrate material indium forms centers similar to DX-like centers in Zn_{x}Cd_{1-x}Te and Cd_{1-x}Mn_{x}Te.
19
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s,p-d Exchange Constants of CdFeSe Semimagnetic Semiconductor

51%
Arciszewska M., Pakuła K., Perez I., Twardowski A.
Acta Physica Polonica A
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1991
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vol. 79
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issue 2-3
345-348
EN
We report determination of s, p-d exchange constants for hexagonal CdFeSe combining exciton splitting and magnetization measurements performed on the same samples.
20
Content available remote

Composition Dependence of the Energy Gap in HgFeSe - Optical Verification

51%
Szuszkiewicz W., Julien C., Bałkanski M., Dybko K., Witkowska B.
Acta Physica Polonica A
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1992
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vol. 82
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issue 5
757-760
EN
Infrared reflectivity was investigated for the mixed Hg_{1-x}Fe_{x}Se crystals for x < 0.1. The theoretical analysis of the experimental curves suggests opening of the energy gap for the composition x = 0.087 at the temperature close to 80 K.
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