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1
Content available remote

Study of Misfit Dislocations Profiles in ZnSe/GaAs Structures by Raman Scattering

100%
Bała W., Drozdowski M., Kozielski M.
Acta Physica Polonica A
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1993
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vol. 84
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issue 4
689-692
EN
In this paper we present the Raman scattering measurements of the ZnSe epilayers grown on (001) GaAs substrate by molecular beam epitaxy method. We have studied dependence of the frequency shift of LO(ZnSe) mode in the Raman spectra vs. thickness of the ZnSe layer. The intensity of LO(ZnSe)/LO(GaAs) ratio vs. orientation angle α of the E vector of the exciting light on the ZnSe/GaAs interface relatively to the sample orientation is presented too.
2
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Characterization of the Band Bending in ZnSe-GaAs Heterojunctions by Raman Scattering

63%
Bała W., Drozdowski M., Kozielski M.
Acta Physica Polonica A
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1991
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vol. 79
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issue 2-3
225-228
EN
The band bending effect at the ZnSe-GaAs interface Was studied by means of Raman scattering induced by electric-field related to longitudinal-optical (LO) phonons. It has been shown that the variation of the band bending in GaAs can be modifled by changes in the electron concentration of ZnSe epilayer and the variation of the sample temperature.
3
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An Investigation of Optical Vibrations in Zn_{3}P_{2}

63%
Misiewicz J., Wrobel J., Clayman B.
Acta Physica Polonica A
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1991
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vol. 79
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issue 2-3
405-409
EN
Reflectivity and transmittivity spectra of Zn_{3}P_{2} in the far infrared region were measured at several temperatures. Raman scattering spectra at 295 K were also measured. Results of these measurements were interpreted in terms of one-phonon and multi-phonon transitions.
4
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Investigation of the Strains at ZnSe/GaAs Interfaces by Raman Scattering

63%
Bala W., Drozdowski M., Kozielski M.
Acta Physica Polonica A
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1991
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vol. 80
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issue 5
723-730
EN
Investigations of the strains at the n-ZnSe epilayers grown on GaAs substrate using polarized Raman spectra are presented. It has been shown that Raman scattering experiment can be used as a method for investigation of the splitting between the heavy- and light-hole bands in n-ZnSe thin films.
5
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Exciton Electroluminescence of ZnSe/ZnO Structures under Biaxial Stress

63%
Bała W., Firszt F., Łęgowski S., Męczyńska H.
Acta Physica Polonica A
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1992
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vol. 82
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issue 5
896-899
EN
The strained ZnSe/ZnO structures grown on (111) ZnSe crystals by plasma oxidation was investigated by electro- and photoluminescence methods. The lines of heavy and light hole excitons under biaxial compressive stress are measured as a function of the temperature.
6
Content available remote

Influence of Free Carrier Concentration on Nonlinear Absorption of n-Type ZnSe Crystals

63%
Sahraoui B., Chevalier R., Nguyen Phu X., Rivoire G., Bała W.
Acta Physica Polonica A
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1996
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vol. 90
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issue 5
1070-1074
EN
The dependence of nonlinear absorption at 532 nm of n-type ZnSe crystals upon annealing temperature and free carrier concentration is reported. The nonlinear optical absorption as well as the efficiency of degenerate four wave mixing of ZnSe are investigated. It is found that the magnitude of the nonlinear absorption decreases with an increase in the electron concentration. The nonlinear refractive index change is estimated.
7
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Photoluminescence, Reflectivity and Raman Investigations of Nanocrystallites in Luminescent Porous Silicon

63%
Bala W., Głowacki G., Łukasiak Z., Drozdowski M., Kozielski M., Nossarzewska-Orłowska E., Brzozowski A.
Acta Physica Polonica A
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1995
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vol. 87
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issue 2
445-448
EN
Raman scattering, reflectivity and photoluminescence measurements of the porous silicon layers prepared on (001) p/p^{+} silicon epitaxial wafers by anodization method are presented. We have studied dependence of the frequency shift and halfwidth of LO mode in Raman spectra and shift of the luminescence peak in photoluminescence spectra vs. anodization conditions.
8
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Content available

Temperature Dependence of the First-Order Raman Phonon Lines in GaS_{0.25}Se_{0.75} Layered Crystals

51%
Gasanly N.
Acta Physica Polonica A
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2002
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vol. 102
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issue 6
801-810
EN
Systematic measurements by Raman scattering of the frequency and line width of the zone-center optical modes in GaS_{0.25}Se_{0.75} layered crystal over the temperature range of 10-300 K are carried out. The analysis of temperature dependence of intralayer modes shows that frequency shift and line broadening are successfully modeled by including the contributions from thermal expansion and lattice anharmonicity. The purely anharmonic contribution (phonon-phonon coupling) is found to be due to three-phonon processes.
9
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Content available

Radiation Effects in DMAAS:Cr Ferroelectric Crystal

51%
Kapustianik V., Czapla Z., Eliyachevskyy Y., Korchak Y., Kulyk B., Rudyk V.
Acta Physica Polonica A
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2003
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vol. 104
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issue 6
571-580
EN
This paper presents the results of investigations of the radiation effects in NH_2(CH_3)_2Al(SO_4)_2×6H_2O crystals doped with chromium. On the basis of absorption spectroscopy and resonance Raman scattering study it has been shown that comparatively low doses of radiation first of all causes recharging of Cr^{3+} on Cr^{4+} ions. Besides, the processes of dehydrogenation and the changes in arrangement of the hydrogen bond network were observed. These changes are followed by distortion of the complexes bonded by such a type of bonds.
10
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Synthesis and Vibration Spectroscopy of Nano-Sized Manganese Oxides

51%
Mironova-Ulmane N., Kuzmin A., Skvortsova V., Chikvaidze G., Sildos I., Grabis J., Jankoviča D., Dindune A., Maiorov M.
Acta Physica Polonica A
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2018
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vol. 133
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issue 4
1013-1016
EN
X-ray diffraction, micro-Raman and the Fourier transform infrared spectroscopies as well as magnetometry measurements were performed on nanosized manganese oxides to probe their phase composition and magnetic properties. It was shown that the XRD method is less sensitive to phase composition of manganese oxide samples than spectroscopic methods. While in some samples the XRD method recognised only the manganosite MnO phase, the Raman and FT-IR methods revealed additionally the presence of the hausmannite Mn₃O₄ phase.
11
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Electrical Resistivity of CrN Thin Films

51%
Batko I., Batkova M., Lofaj F.
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vol. 126
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issue 1
415-416
EN
The work is focused on the measurements of electrical resistivity of CrN thin films deposited on glass substrates by DC-magnetron sputtering in Ar+N_{2} atmosphere. The studied samples reveal semiconducting behaviour of electrical resistivity in the whole range of tested preparation parameters (such as pressure and composition of Ar-N_{2} mixture), whereas the electrical transport regime is strongly influenced by parameters of preparation. Numerical analysis of the experimental data showed that electrical transport can be adequately described in terms of variable-range hopping conduction in selected temperature intervals. Moreover, S-shaped anomaly in ρ(T) dependence, being expected to be a consequence of phase transition to a low-temperature antiferromagnetic orthorhombic phase, has been observed for sample with the highest concentration of N_{2} in the temperature interval of 220-250 K. The obtained results indicate that technology processes typically used for preparation of CrN coatings represent a promising potential to develop also high sensitivity cryogenic sensors for high magnetic fields applications.
12
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Raman Spectroscopy of LiFePO_4 and Li_3V_2(PO_4)_3 Prepared as Cathode Materials

51%
Ziółkowska D., Korona K., Kamińska M., Grzanka E., Andrzejczuk M., Wu S., Chen M.
Acta Physica Polonica A
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2011
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vol. 120
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issue 5
973-975
EN
Structure of samples of lithium iron vanadium phosphates of different compositions were investigated by X-rays, electron microscopy and Raman spectroscopy. The investigated salts were mainly of olivine-like and NASICON-like structures. The X-ray diffraction and the Raman scattering show different crystalline structures, which is probably caused by difference between cores of the crystallites (probed by X-rays) and their shells (probed by the Raman scattering). Most of the Raman spectra were identified with previously published data, however in the samples with high vanadium concentration we have observed new, not reported earlier modes at 835 cm^{-1} and 877 cm^{-1}, that we identified as oscillations related to V_2O_7^{4-} or VO_4^{3-} anions.
13
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Micro-Raman Study of BiFeO_3 Thin Films Fabricated by Chemical Solution Deposition Using Different Bi/Fe Ratio Precursors

51%
Nakamura T., Fukumura H., Hasuike N., Harima H., Nakamura Y., Kisoda K., Nakashima S., Okuyama M.
Acta Physica Polonica A
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2009
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vol. 116
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issue 1
72-74
EN
BiFeO_3 thin films were grown by chemical solution deposition using precursors with different elemental ratios, Bi/Fe = 1.1/1.0, 1.0/1.0 and 1.0/1.1. All the samples consisted of two easily distinguishable components of crystalline and amorphous phases. We have found that the electric properties of BiFeO_3 thin films are closely connected to the crystallinity of the films.
14
Publication available in full text mode
Content available

Low-Temperature Raman Scattering in TlGa_xIn_{1-x}S_2 Layered Mixed Crystals: Compositional Dependence of the Mode Frequencies and Line Shapes

51%
Gasanly N., Yuksek N.
Acta Physica Polonica A
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2005
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vol. 108
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issue 6
997-1003
EN
The Raman spectra of TlGa_xIn_{1-x}S_2 layered mixed crystals were studied for a wide range of composition (0≤x≤1) at T=50 K. The effect of crystal disorder on the line width broadening of the Raman-active modes are discussed. The asymmetry in the Raman line shape is analyzed for two interlayer and intralayer modes exhibiting one-mode behavior.
15
Content available remote

Some Aspects of Solid State Radioluminescence

51%
Wojtowicz A.
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vol. 95
|
issue 1
165-178
EN
In this paper we review results of radioluminescence studies on two scintillator materials, LuAlO_{3} and YAlO_{3}, activated with Ce. The experiments include measurements of ther moluminescence, isothermal phosphorescence decays, scintillation light yield as function of temperature, and scintillation time profiles under gamma excitation. Experimental results are interpreted in the frame of a simple kinetic model that includes a number of electron traps. We have identified and characterized a number of deep and shallow traps and demonstrated that traps in LuAlO_{3}:Ce are deeper than corresponding traps in YAlO_{3}:Ce. Unlike deep traps which are responsible for some scintillation light loss but otherwise do not have any impact on generation of scintillation light, shallow traps are shown to actively interfere with the process of radiative recombination via Ce ions. We demonstrate that shallow traps are responsible for some as yet unexplained observations including a higher room temperature light yield of YAlO_{3}:Ce and its longer scintillation decay time, as well as a longer scintillation rise time in LuAlO_{3}:Ce.
16
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Raman Scattering Study of (Sr,Ca)_{10}Cu_{17}O_{29} Single Crystals

51%
Strzeszewski J., Szymczak H., Leonyuk L., Szymczak R.
Acta Physica Polonica A
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2000
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vol. 98
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issue 4
429-439
EN
Polarized Raman spectra of high temperature superconducting single crystals of A_{10}Cu_{17}O_{29} (A_{10}=Ca_{4.7}Sr_{4.1}Bi_{0.3}) were studied in various scattering configurations in the range of 40-700cm^{-1}. In very distinctive spectra there were found over 20 peaks. It was observed that the flat continuum of electronic excitations in the normal state was redistributed below the critical temperature. The frequency dependent redistribution is consistent with the value of energy gap estimated using tunnelling spectroscopy techniques.
17
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Synthesis and Characterization of Mn-Doped BiFeO_3 Nanoparticles

51%
Fukumura H., Matsui S., Tonari N., Nakamura T., Hasuike N., Nishio K., Isshiki T., Harima H., Kisoda K.
Acta Physica Polonica A
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2009
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vol. 116
|
issue 1
47-50
EN
BiFeO_3 is a multiferroic material showing antiferromagnetic ordering and ferroelectric behavior simultaneously. Here, Mn-doped BiFeO_3 nanoparticles were synthesized up to 10% of Mn composition by a sol-gel process. The samples showed high crystallinity with no secondary phase up to 2% of Mn doping. A phonon peak at 1250 cm^{-1} in undoped BiFeO_3 showed anomalous intensity enhancement in the magnetically ordered phase below T_N = 643 K due to a spin-phonon coupling. This behavior was less pronounced in the Mn-doped samples, suggesting a suppression of magnetic ordering between Fe^{3+} spins by Mn doping.
18
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Optical in situ Study of Reduction/Oxidation Processes in Cr,Mg:YAG Epitaxial Film

45%
Buryy O., Ubizskii S., Syvorotka I., Becker K.
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EN
The changes of the optical absorption spectra of Cr,Mg:YAG epitaxial film caused by high-temperature redox treatment are investigated by means of in situ spectroscopy. The spectra were registered in the visible and near-IR spectral regions at temperatures up to 1100 K. The kinetics of optical absorption changing were obtained in the temperature range from 936 K to 1091 K and were described by mathematical model connecting the chromium recharging process with oxygen vacancies diffusion. The parameters of the model were determined from the approximations of the experimental kinetics.
19
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Structural study of TiO2 thin films by micro-Raman spectroscopy

32%
Niilisk A., Moppel M., Pärs M., Sildos I., Jantson T., Avarmaa T., Jaaniso R., Aarik J.
Open Physics
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2006
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vol. 4
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issue 1
105-116
EN
The Raman spectroscopy method was used for structural characterization of TiO2 thin films prepared by atomic layer deposition (ALD) and pulsed laser deposition (PLD) on fused silica and single-crystal silicon and sapphire substrates. Using ALD, anatase thin films were grown on silica and silicon substrates at temperatures 125–425 °C. At higher deposition temperatures, mixed anatase and rutile phases grew on these substrates. Post-growth annealing resulted in anatase-to-rutile phase transitions at 750 °C in the case of pure anatase films. The films that contained chlorine residues and were amorphous in their as-grown stage transformed into anatase phase at 400 °C and retained this phase even after annealing at 900 °C. On single crystal sapphire substrates, phase-pure rutile films were obtained by ALD at 425 °C and higher temperatures without additional annealing. Thin films that predominantly contained brookite phase were grown by PLD on silica substrates using rutile as a starting material.
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