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1
Content available remote

Native Defects in Gallium Arsenide Grown by Synthesis, Solute Diffusion Method

100%
Fronc K., Mąkosa A., Wosiński T.
Acta Physica Polonica A
|
1991
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vol. 80
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issue 3
349-352
EN
High-purity n-type GaAs crystal was grown by the Synthesis, Solute Diffusion (SSD) method. Deep Level Transient Spectroscopy (DLTS) characterization of the crystal revealed three deep traps related to native defects. Microscopic origin of the traps is discussed and prospective use of SSD-grown GaAs as a bulk material with the high luminescence efficiency is emphasized.
2
Content available remote

Optically Detected Magnetic Resonance Studies of Te-Related Shallow Donors in Al_{x}Ga_{1-x}As

100%
Godlewski M., Fronc K., Chen W., Monemar B.
Acta Physica Polonica A
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1991
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vol. 80
|
issue 3
341-344
EN
The first studies of the Optically Detected Magnetic Resonance (ODMR) of Te-doped (x = 0.42) are presented. The ODMR data indicate an efficient energy transfer between epilayer and GaAs substrate.
3
Content available remote

Impact Ionization Driven Chaotic Photoluminescence Oscillations in Ga_{0.47}In_{0.53}As

88%
Godlewski M., Fronc K., Gajewska M., Chen W., Monemar B.
Acta Physica Polonica A
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1991
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vol. 80
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issue 2
271-274
EN
A new application of the Optically Detected Cyclotron Resonance (ODCR) is presented. We report impact ionization studies of bound exciton: (BE) and shallow donor related recombination processes in Ga_{0.47}In_{0.53}As. An appearance of chaotic oscillations in photoluminescence (PL) intensity is observed under condition of impact ionization of deeper donors.
4
Content available remote

Observation of Two-Dimensional Electron Gas in LPE-Grown GaInAs-InP Heterostructures

88%
Fronc K., Grabecki G., Wróbel J., Dietl T., Gajewska M.
Acta Physica Polonica A
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1991
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vol. 80
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issue 3
449-452
EN
A series of GaInAs/InP heterostructures was grown by liquid phase epitaxy. The heterostructures were characterized by magnetotransport measurements carried out down to 1.8 K and up 10 T. The results demonstrate the existence of the high-mobility two-dimensional electron gas in the narrow-gap GaInAs as well as the presence of residual conductance through the InP buffer layer.
5
Content available remote

Photo-ESR Study of the DX to Shallow Donor Conversion in Te Doped Al_{x}Ga_{1-x}As

88%
Surma M., Żytkiewicz Z., Fronc K., Stalinga P., Godlewski M.
Acta Physica Polonica A
|
1993
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vol. 84
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issue 4
757-760
EN
Results of detailed electron spin resonance (ESR) study of Te doped Al_{x}Ga_{1-x}As epilayers with x = 0.41, 0.42, and 0.5 Al fractions are presented. It is shown that the ESR signal observed critically depends on cooling steps and that the shallow donor ESR signal can be observed prior to illumination. The first ESR study of AlGaAs layers with removed GaAs substrate are presented. The mechanism of the enhanced photosensitivity of the ESR signal is explained. It is found very paradoxical that the ESR signals decreases upon the illumination even though shallow donor concentration is increased.
6
Content available remote

Mechanical and Electrical Properties, of ZnO-Nanowire/Si-Substrate Junctions Studied by Scanning Probe Microscopy

76%
Aleszkiewicz M., Fronc K., Wróbel J., Klepka M., Wojtowicz T., Karczewski G.
Acta Physica Polonica A
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2007
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vol. 112
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issue 2
255-260
EN
Scanning tunneling spectroscopy was used to check the tunneling I-V characteristics of junctions formed by n-ZnO nanowires deposited on Si substrates with n- and p-type electrical conductivity (i.e. n-ZnO nanowire/n-Si and n-ZnO nanowire/p-Si junctions, respectively). Simultaneously, several phenomena which influence the measured I-V spectra were studied by atomic force microscopy. These influencing factors are: the deposition density of the nanowires, the possibility of surface modification by tip movement (difference in attraction forces between nanowires and the p-Si and n-Si) and the aging of the surface.
7
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Magnetic Force Microscopy Study of Zn_{1-x}Co_{x}O Nanowires Grown by Rapid Thermal Evaporation

64%
Aleszkiewicz M., Fronc K., Aleszkiewicz P., Zaleszczyk W., Dziawa P., Wojciechowski T., Wojtowicz T., Karczewski G.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
865-867
EN
In this work we studied domain structure of Zn_{1-x}Co_{x}O nanowires which are single arms of tetrapode crystals. The as-grown material exhibits hysteretic behavior even at room temperature as revealed by SQUID mesurements. In order to get insight into the magnetic properties of individual tetrapodes they were dismembered into nanowires of nanometric diameters, deposited on a flat substrate and imaged by magnetic force microscopy. A magnetic interaction between the magnetic force microscopy probe and single nanowires has been detected which confirms that nanometric volume of the material possesses a magnetic moment. The magnetic force microscopy contrast is attractively independent of the tip magnetization direction which indicates that shape anisotropy of nanowires is not strong enough to prevent occurrence of tip-induced magnetic field disturbance.
8
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Spectroscopy of Indirect Excitons in Vertically Stacked CdTe Quantum Dot Structures

64%
Kukliński K., Kłopotowski Ł., Fronc K., Wojnar P., Wojciechowski T., Czapkiewicz M., Kossut J., Karczewski G., Wojtowicz T.
Acta Physica Polonica A
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2011
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vol. 120
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issue 5
856-858
EN
We show that by means of an electric field we can tune the energy levels in vertical quantum dot pairs and study transitions related to recombination of direct and indirect excitons. With decreasing the reverse bias, we observe both the blue- and red-shifted indirect exciton transitions. Based on the band profile of our device, we conclude that the former corresponds to the recombination of the electron and hole localized in the top and the bottom dot, respectively and the latter is related to the recombination of the electron and hole localized in the bottom and the top dot, respectively.
9
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Atomic Force Microscopy Study of a Voltage Effect on CdZnTe Crystal Dimensions

64%
Aleszkiewicz P., Wojciechowski T., Fronc K., Kolkovsky V., Janik E., Jakieła R., Mycielski A., Karczewski G., Aleszkiewicz M.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1041-1047
EN
In this work we studied the influence of an external electric voltage on spatial dimensions of CdZnTe mixed crystals. In order to get an absolute magnitude of the sample thickness and to gain insight to the changes of lateral dimension, in quasi-bulk 3 μm thick CdZnTe layers grown by molecular beam epitaxy square craters were formed by ion sputtering in a secondary ion mass spectrometer. The vertical and lateral dimensions of the craters were studied by the atomic force microscopy. The atomic force microscopy measurement revealed that the thickness of the CdZnTe layer increases in a result of applying a single voltage pulse to the sample surface and decreases reversibly after applying reversely biased voltage. The voltage triggering was high enough to switch the conductivity state of the sample i.e., the effect of thickness change is accompanied by the effect of conductivity switching. The thickness change is significant, reaching several percents of the entire layer thickness.
10
Content available remote

Photoluminescence and Thermoluminescence of the Oxygen-Deficient YAG, YAP, and YAM Phosphors

64%
Zhydachevskyy Y., Kamińska I., Glowacki M., Kilian A., Ubizskii S., Bilski P., Berkowski M., Fronc K., Elbaum D., Suchocki A.
Acta Physica Polonica A
|
2018
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vol. 133
|
issue 4
977-980
EN
Photoluminescence and thermoluminescence of the oxygen-deficient Y₃Al₅O₁₂ (YAG), YAlO₃ (YAP) and Y₄Al₂O₉ (YAM) ceramics has been studied. Corresponding ceramic samples prepared by the same way however in oxidizing conditions (in air) were studied for comparison. The observed luminescent properties of the materials are related to the F-type centers created on the basis of oxygen vacancies, antisite (Y_{Al}) defects and uncontrolled Tb³⁺ impurity ions.
11
Content available remote

Influence of Configuration Mixing on Energies and Recombination Dynamics of Excitonic States in CdTe/ZnTe Quantum Dots

64%
Smoleński T., Kazimierczuk T., Goryca M., Kossacki P., Gaj J., Wojnar P., Fronc K., Korkusiński M., Hawrylak P.
Acta Physica Polonica A
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2011
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vol. 119
|
issue 5
615-617
EN
We study experimentally and theoretically excitonic recombination processes in CdTe/ZnTe quantum dots. The single quantum dot photoluminescence spectrum was observed and emission lines from X, X^-, X^+ and 2X excitonic states were identified. Experimental results were analysed in the theoretical model based on the effective mass approximation. Numerical calculations of energy positions and recombination probabilities of X, X^-, X^+ and 2X were performed. Computed results reproduce correctly the order and relative positions of emission lines and ratios of radiative lifetimes.
12
Content available remote

Magnetoplasmons in a High Electron Mobility GaAs/AlGaAs Heterostructure

64%
Białek M., Karpierz K., Piętka B., Grynberg M., Łusakowski J., Czapkiewicz M., Fronc K., Wróbel J., Umansky V.
Acta Physica Polonica A
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2012
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vol. 122
|
issue 6
1096-1098
EN
We have observed a multimode spectrum of magnetoplasmons in the Hall bars processed on a high electron mobility GaAs/AlGaAs heterostructure. We have found that the dispersion relation of these excitation follows square root dependence. Calculated wavelength of the fundamental magnetoplasmon mode fits to the width of sample.
13
Content available remote

Physical Properties of ZnCoO Tetrapods and Nanofibers

52%
Gas K., Fronc K., Dziawa P., Knoff W., Wojciechowski T., Zaleszczyk W., Baranowska-Korczyc A., Morhange J., Paszkowicz W., Elbaum D., Karczewski G., Wojtowicz T., Szuszkiewicz W.
Acta Physica Polonica A
|
2009
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vol. 116
|
issue 5
868-870
EN
In this paper the physical properties of two types of Co-doped ZnO nanostructures: tetrapods and nanofibers grown by a rapid thermal evaporation process and prepared by the electrospinning technique, respectively, were investigated and analyzed. Surface morphology of the samples was examined using scanning electron microscopy. X-ray diffraction measurements showed hexagonal wurtzite crystal structure of both types of investigated nanostructures. Both X-ray diffraction and Raman scattering data confirmed high phase purity of the samples. The magnetic properties studied with the use of the SQUID magnetometer confirmed a presence of ferromagnetic order in analyzed nanostructures. The observed photoluminescence spectra exhibited two groups of lines. The first one, in the ultraviolet spectral range, is due to the optical transitions close to ZnO band gap, the second one in the red region is most probably related to the Co^{2+} d-d internal transitions. The influence of native defects on the optical properties is also shown and discussed. All results reported here lead us to the conclusion that in the mixed crystal nanostructures obtained, a fraction of the Zn^{2+} ions is substituted by Co^{2+} ions.
14
Content available remote

Photoluminescence Properties of ZnO Nanowires Grown on Ni Substrate

52%
Zaleszczyk W., Fronc K., Przeździecka E., Janik E., Czapkiewicz M., Wróbel J., Paszkowicz W., Kłopotowski Ł., Karczewski G., Wojtowicz T., Presz A.
Acta Physica Polonica A
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2008
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vol. 114
|
issue 5
1451-1456
EN
Photoluminescence studies of zinc oxide nanowires produced by a carbo-thermal method on a nickel foil substrate are reported. Two types of as-grown samples: the first - containing only buffer film, and the second - containing both zinc oxide nanowires and buffer film grown in the same technological process, were investigated by means of the temperature-dependent photoluminescence. X-ray diffraction measurements of buffer film show that it is polycrystalline and is composed from wurtzite-type ZnO (main phase) and includes minority phases: rock salt type (Ni,Zn)O and hexagonal C₃N₄. The shape of the apparently monocrystalline nanowires is characterized by hexagonal section matching with the expectations of the hexagonal ZnO structure. The presence of LO-phonon replicas in photoluminescence spectra for the second sample is used as an argument for confirmation that ZnO nanowires are single crystalline. The method of growth of ZnO nanowires on nickel oxide opens perspectives to produce Zn_{1-x}Ni_{x}O diluted magnetic semiconductor nanowires.
15
Content available remote

Photoluminescence Properties of ZnO and ZnCdO Nanowires

52%
Zaleszczyk W., Fronc K., Aleszkiewicz M., Paszkowicz W., Wróbel J., Dłużewski P., Kret S., Klepka M., Kłopotowski Ł., Karczewski G., Wojtowicz T.
Acta Physica Polonica A
|
2007
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vol. 112
|
issue 2
357-362
EN
We report on the photoluminescence studies of ZnO and ZnCdO nanowires grown on SiO_2/Si substrates by low-pressure vapor phase synthesis. X-ray diffraction and transmission electron microscopy measurements show that the crystallographic structure of these ZnO and ZnCdO nanowires is of wurtzite-type with a high crystal perfection. Surface morphology of samples was determined by scanning electron microscopy and atomic force microscopy. The photoluminescence spectra of as-grown nanowires, nanowires extracted from the substrate and deposited onto Si wafer, and nanowires dispersed in ethanol by sonication were investigated at room temperature and compared to each other. The temperature dependence of the near band-gap photoluminescence emitted by the as-grown nanowires was also measured and analyzed.
16
Content available remote

Morphology and Selected Properties of Core/Shell ZnTe-Based Nanowire Structures Containing ZnO

52%
Gas K., Janik E., Zaleszczyk W., Pasternak I., Dynowska E., Fronc K., Kolkovsky V., Kret S., Morhange J., Reszka A., Wiater M., Caliebe W., Karczewski G., Kowalski B., Szuszkiewicz W., Wojtowicz T.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
612-614
EN
We report on an approach to fabricate ZnTe-based core/shell radial heterostructures containing ZnO, as well as on some of their physical properties. The molecular beam epitaxy grown ZnTe nanowires constituted the core of the investigated structures and the ZnO shells were obtained by thermal oxidation of ZnTe NWs. The influence of the parameters characterizing the oxidation process on selected properties of core/shell NWs were examined. Scanning electron microscopy revealed changes of the NWs morphology for various conditions of the oxidation process. X-ray diffraction, high resolution transmission electron microscopy, and Raman scattering measurements were applied to reveal the presence of ZnTe single crystal core and polycrystalline ZnO-shell of investigated structure.
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