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Wyszukujesz frazę "Karczewski, M." wg kryterium: Autor


Tytuł:
Conductance Fluctuations in Quantum Wires of n-CdTe and n-Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te
Autorzy:
Jaroszyński, J.
Wróbel, J.
Sawicki, M.
Skośkiewicz, T.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Dietl, T.
Kamińska, E.
Papis, E.
Barcz, A.
Piotrowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/1934061.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Rn
73.61.Ga
73.20.Fz
Opis:
We present millikelvin studies of magnetoconductance in submicron wires of In-doped n$\text{}^{+}$-CdTe and n$\text{}^{+}$-Cd$\text{}_{0.99}$Mn$\text{}_{0.01}$Te epilayers. Weak-field magnetoresistance which arises from quantum localization as well as universal conductance fluctuations have been observed. The exchange coupling to magnetic impurities is shown to decrease the correlation field of the fluctuations. This novel effect is interpreted by invoking a new driving mechanism of the magnetoconductance fluctuations - the redistribution of the electrons between energy levels of the system, induced by the giant s-d spin-splitting of the electronic states.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 1000-1004
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cubic MnTe - Growth by Molecular Beam Epitaxy and Basic Structural Characterization
Autorzy:
Zakrzewski, A.
Janik, E.
Dynowska, E.
Leszczyński, M.
Kutrowski, M.
Wojtowicz, T.
Karczewski, G.
Bąk-Misiuk, J.
Domagała, J.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1873112.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
68.55.Bd
68.55.Jk
Opis:
We report on growth by molecular beam epitaxy of thick layers of MnTe with zinc blende structure. Films as thick as 5.6 µm were obtained. Characterization by X-ray diffraction proved their good structural quality. We determined the lattice constant and its temperature dependence. Broad luminescence due to internal Mn$\text{}^{2+}$- transitions was observed. It showed an unexpected temperature dependence.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 433-436
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Digital Magnetic Quantum Wells for the Study of Interface Sharpness of Molecular Beam Epitaxy Grown Structures
Autorzy:
Wojtowicz, T.
Karczewski, G.
Żakrzewski, A.
Kutrowski, M.
Janik, E.
Dynowska, E.
Kopalko, K.
Kret, S.
Kossut, J.
Laval, J. Y.
Powiązania:
https://bibliotekanauki.pl/articles/1931933.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
78.55.Et
Opis:
We report on the growth and basic characterization of digital magnetic quantum wells, that is, quantum wells in which the well material is itself a short period superlattice composed of alternating diluted magnetic and nonmagnetic semiconductor layers each only a few monolayers thick. These novel structures can be useful in a variety of studies, including studies of barrier-well interface sharpness.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 165-168
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exciton Dynamics in CdTe/CdMnTe Multiquantum Well Structures Grown by Molecular Beam. Epitaxy on GaAs Substrate
Autorzy:
Godlewski, M.
Koziarska, B.
Suchocki, A.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Bergman, J.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1934057.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.60.-p
78.47.+p
73.20.Fz
71.35.+z
Opis:
The results of picosecond photoluminescence kinetics of four different CdTe/CdMnTe multiquantum well structures grown by MBE on GaAs substrates are presented. The experimental results show that excitons in CdTe quantum wells are strongly localized by potential fluctuations. Photoluminescence decay times of the localized excitons are considerably shorter (about 120 ps) than those reported for free or quasi-free excitons. An influence of Mn in the barriers on exciton properties is demonstrated. For narrow quantum wells as well as for the multiquantum well structure with the highest Mn mole fraction the excitons migrate during their decay to the states with a lower potential energy. Longer decay times are observed for quasi-localized excitons. We show also that for strongly localized excitons the energy transfer between localized and donor bound excitons is less efficient.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 985-989
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Indium Doping of CdTe Grown by Molecular Beam Epitaxy
Autorzy:
Karczewski, G.
Zakrzewski, A.
Kutrowski, M.
Jaroszyński, J.
Dobrowolski, W.
Grodzicka, E.
Janik, E.
Wojtowicz, T.
Kossut, J.
Barcz, A.
Powiązania:
https://bibliotekanauki.pl/articles/1932089.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Ln
73.61.Ga
Opis:
We report on n-type indium doping of CdTe films grown by molecular beam epitaxy on (001) GaAs substrates. By adjusting the flux of In atoms we can precisely control the carrier concentration over three orders of magnitude - from 8 × 10$\text{}^{14}$ up to 1.3 × 10$\text{}^{18}$ cm$\text{}^{-3}$. In agreement with earlier reports we confirmed that Cd overpressure plays an important role in the doping process. The doping appears to be most effective for Cd/Te pressure ratio of 1.5. For this value of Cd/Te pressure ratio essentially 100% efficiency of doping is achieved at low In concentrations (< 10$\text{}^{18}$ cm$\text{}^{-3}$). At higher In concentrations acceptor impurities compensate shallow donors limiting the concentration of free carriers.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 241-244
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence Decay in Deep Quantum Wells CdTe/Cd_{0.5}Mn_{0.5}Te at Room Temperature
Autorzy:
Kowalczyk, L.
Fancey, S.
Buller, G.
Massa, J.
Kutrowski, M.
Janik, E.
Karczewski, G.
Wojtowicz, T.
Zakrzewski, A.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1876908.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Hf
78.47.+p
78.55.Et
Opis:
Time-resolved photoluminescence was used to study exciton recombination in deep CdTe/Cd_{0.5}Mn_{0.5}Te single quantum well. The width of the investigated well was 100 A. The study was performed at room temperature. The lifetime of the exciton determined in this work has a value comparable to that observed in shallow CdTe/Cd_{0.85}Mn_{0.15}Te quantum wells. A strong enhancement of the photoluminescence decay time with increasing intensity of the exciting laser beam is observed which is indicative of saturation of the non-radiative recombination centers.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 508-513
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Characterization of Molecular Beam Epitaxy Grown $Cd_{1-x}$Mn$\text{}_{x}$Te Structures
Autorzy:
Sawicki, M.
Kolesnik, S.
Wojtowicz, T.
Karczewski, G.
Janik, E.
Kutrowski, M.
Żakrzewski, A.
Dynowska, E.
Dietl, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1931934.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
75.50.Rr
75.50.Ee
Opis:
The paper reports on the application of SQUID magnetometry to probe magnetic ion distribution in epilayers and at interfaces of diluted magnetic semiconductors. We present also new results on the possible influence of the magnetic confinement on the formation of the spin-glass phase, and on antiferromagnetic phase transition in zinc-blende MnTe.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 169-172
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Search for Dimensional Effects in Spin-Glass Transition in Thin Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te Multilayers
Autorzy:
Sawicki, M.
Dietl, T.
Skośkiewicz, T.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1943818.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Rr
75.50.Lk
75.30.Kz
75.50.-y
Opis:
SQUID magnetic measurements of CdTe/Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te, x ≃ 0.5, multi-layers with different CdMnTe layer thickness w reveal the persistence of the spin-glass irreversibilities down to ≃ 16 Å thin layers, i.e., well beyond the previously postulated 40 Å as a quasi-2D threshold. The freezing temperature T$\text{}_{f}$ is found to be a monotonic function of w, and it obeys a scaling law T$\text{}_{f}$ ∝ w$\text{}^{a}$, with a 0.8 similar to that for canonical spin-glasses. Magnetic properties of all studied structures are found to be independent of the orientation of the magnetic field.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 1038-1042
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial Correlations of Donor Charges in MBE CdTe
Autorzy:
Suski, T.
Wiśniewski, P.
Litwin-Staszewska, E.
Wasik, D.
Przybytek, J.
Baj, M.
Karczewski, G.
Wojtowicz, T.
Zakrzewski, A.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1934021.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ey
71.55.Gs
Opis:
We present experimental evidence that at high pressures indium donors in CdTe localize electrons in spatially correlated manner. We have studied Hall mobility, μ$\text{}_{H}$, as a function of electron concentration, n$\text{}_{H}$, at T=77 K. Changes of n$\text{}_{H}$ have been achieved by two methods. High pressure freeze-out of electrons onto localized states of In-donors leads to the mobility enhancement with respect to the situation when n$\text{}_{H}$ has been modified by means of a subsequent annealing of the sample. As a result, depending on the degree of spatial correlations in the impurity charges arrangement, different values of μ$\text{}_{H}$ correspond to the same value of n$\text{}_{H}$. The variation of mobility with electron concentration suggests that the localized state of In-donor represents likely negatively charged DX state.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 929-932
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Study of Photoluminescence from Deep CdTe/Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te Quantum Wells
Autorzy:
Kutrowski, M.
Wojtowicz, T.
Karczewski, G.
Kopalko, K.
Zakrzewski, A. K.
Janik, E.
Grasza, K.
Łusakowska, E.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1876361.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
78.55.Et
Opis:
The photoluminescence studies in CdTe/CdMnTe quantum wells are reported in the temperature range 10-300 K. The MnTe concentration in the barriers is x = 0.3, 0.5, 0.63 and 0.68. Thus the potential wells in our samples are very deep, of the order of ≈ 800 meV in the conduction band and ≈ 200 meV in the valence band in the case of the x = 0.68 sample. In spite of the large lattice mismatch (related to high x value) between the wells and the barriers the observed line widths are as narrow as 2 meV in the case of 100 Å. Clear manifestations of internal strain are observed. In particular, the temperature coefficient of the luminescence energies shows strong dependence on the width of wells.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 500-504
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unusual Time Dependence of Magnetization Relaxation in MBE Grown Epilayer of CdMnTe
Autorzy:
Witowski, A. M.
Moll, H. P.
Wyder, P.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1934049.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.60.Wm
76.30.Fc
Opis:
The temporal behavior of the magnetization due to the spin-lattice relaxation for bulk and MBE grown epilayer of CdMnTe is compared. The time dependence of the epilayer magnetization changes (dM/dt) is nonmonotonic. After the main part, a second structure appears. It can be explained only by the assumption of energy storage and a delayed additional rise of specimen temperature. The nature of the storage is unknown.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 953-956
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
(120)-Oriented CdTe/CdMnTe Quantum Well Structures Grown by Molecular Beam Epitaxy
Autorzy:
Kutrowski, M.
Karczewski, G.
Cywiński, G.
Surma, M.
Grasza, K.
Łusakowska, E.
Kossut, J.
Wojtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1952037.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
78.55.Et
Opis:
We report on the MBE growth and magnetooptical studies of (120)-oriented CdTe/CdMnTe quantum well structures. The quality of structures, as evaluated by the photoluminescence line width, was as good as that of the best structures grown in ⟨100⟩ direction. No spin splitting enhancement, expected theoretically, due to the reduction of the antiferromagnetic interaction between Mn ions in CdTe/CdMnTe digital alloy quantum wells grown along ⟨120⟩ direction was observed.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 879-882
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te Parabolic Quantum Wells
Autorzy:
Wojtowicz, T.
Kutrowski, M.
Cywiński, G.
Dynowska, E.
Karczewski, G.
Kossut, J.
Fiederling, R.
Mackh, G.
Zehnder, U.
Ossau, W.
Powiązania:
https://bibliotekanauki.pl/articles/1952428.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
78.55.Et
Opis:
We report on the growth and optical studies of II-VI semiconductor parabolic quantum wells made of Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te for a broad range of quantum well widths and Mn molar fractions x. Photoluminescence excitation spectra revealed several series of peaks equidistant in energy associated with interband optical transitions between harmonic oscillator levels. From the analysis of the spectra the valence band offset Q$\text{}_{hh}$ = 0.44±0.1 was determined for the CdTe/Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te system.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 977-980
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization and Selected Physical Properties of CdTe/MnTe Short Period Strained Superlattices
Autorzy:
Szuszkiewicz, W.
Dynowska, E.
Bąk-Misiuk, J.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Jouanne, M.
Powiązania:
https://bibliotekanauki.pl/articles/1952708.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.-e
78.30.Fs
Opis:
Phonon excitations in (CdTe)$\text{}_{12}$/(MnTe)$\text{}_{n}$ (100) superlattices (n=2, 4, 8) were investigated at 295 K and 25 K with the use of Raman scattering. From the "folded" phonon frequencies the elastic constant c$\text{}_{11}$ value for MnTe was estimated. The strain arising from lattice mismatch (determined by X-ray diffraction) results in shifts of MnTe and CdTe "confined" LO phonon frequencies. For the precise determination of LO phonon dispersions an additional shift due to Mn diffusion at the CdTe/MnTe interface should be taken into account.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 1090-1094
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Optical Properties of CdTe/CdMnTe Quantum Wells Grown by Molecular Beam and Atomic Layer Epitaxy
Autorzy:
Godlewski, M.
Kopalko, K.
Wojtowicz, T.
Karczewski, G.
Kossut, J.
Bergman, J. P.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1952470.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.+z
78.47.+p
78.55.Et
Opis:
Optical properties of a series of CdTe/CdMnTe multi quantum well structures grown with MBE and ALE (CdTe quantum wells only) methods are compared. Based on the results of the photoluminescence experiments we conclude that the ALE growth leads to a different lateral scale of quantum well width fluctuations, which results in different exciton properties in two multi quantum well systems studied. In the wells grown with ALE method excitons are less localized. They can migrate in a quantum well plane between quantum well regions varying in thickness by 1 monolayer.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 1012-1016
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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