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Wyszukujesz frazę "Wójtowicz, G." wg kryterium: Autor


Tytuł:
Weakly Diluted Magnetic CdTe/Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te Semiconductor Structures Grown by MBE
Autorzy:
Wojtowicz, Τ.
Karczewski, G.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933693.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
78.55.Et
Opis:
In this paper we review the results of our effort to grow layers and low-dimensional structures containing Cd$\text{}_{1-x}$Μn$\text{}_{x}$Te diluted magnetic semiconductor with relatively high values of Mn molar fraction x. A high quality of the structures grown so far is demonstrated by making use of results of several selected experiments. In the case of the epilayers having bulk-like thickness with x ≥ 0.7 we discuss, in particular, the magnetic phase diagram as well as we report on collective spin excitation (magnons) observed in Raman scattering experiments. The discussion of the growth of different quantum wells, including rectangular, digital, parabolic and wedge quantum wells, is accompanied by a brief overview of their optical and magnetooptical properties. These results include first measurements concerning magnetic polarons in quantum wells embedded in Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te barriers with 0.4 ≤ x ≤ 0.8. Finally, we report on the present status of the search for dimensional effects in the spin-glass phase performed with the use of our specially designed superlattice structures.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 631-642
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Epitaxial Growths of II-VI Compounds on (110) Substrates
Autorzy:
Cywiński, G.
Wojtowicz, T.
Kopalko, K.
Karczewski, G.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1969044.pdf
Data publikacji:
1998-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.-a
Opis:
We studied epitaxial growth conditions of II-VI semiconductors on (110) substrates, which is indispensable for fabrication of T-shaped quantum wire structures. We experimented with different types of (110)-oriented substrates and monitored the surface quality of deposited layers in situ by reflection high energy electron diffraction and ex situ by photoluminescence. The aim of this work is to find optimum growth conditions of II-VI compounds on a cleaved edge of a superlattice as required by the overgrowth method.
Źródło:
Acta Physica Polonica A; 1998, 94, 2; 281-284
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Search for T-Shaped Quantum Wires in CdTe/CdMg(Mn)Te System
Autorzy:
Cywiński, G.
Wojtowicz, T.
Karczewski, G.
Kossut, J.
Gębicki, W.
Powiązania:
https://bibliotekanauki.pl/articles/1969038.pdf
Data publikacji:
1998-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Rn
73.20.Dx
85.40.Ux
Opis:
We attempted to produce and to investigate T-shaped wire structures of II-VI compounds. Our samples were grown on GaAs hybrid substrates in a two-stage growth process. The photoluminescence measurements resulted into two different possible polarization behaviors of recorder signal. We interpret one of these behaviors as due to quantum wire formation.
Źródło:
Acta Physica Polonica A; 1998, 94, 2; 277-280
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Graded Quantum Well Structures Made of Diluted Magnetic Semiconductors
Autorzy:
Wojtowicz, T.
Kutrowski, M.
Karczewski, G.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1968998.pdf
Data publikacji:
1998-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
78.55.Et
Opis:
In this paper we review results of studies of two types of spatially graded quantum well structures containing various layers of diluted magnetic semiconductors Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te or Cd$\text{}_{1-x-y}$Mn$\text{}_{x}$Mg$\text{}_{y}$Te. The design of the structures has been recently proposed by us and suitable samples have been grown by a modified molecular beam epitaxy method. In the structures of the first type a digital profiling of the composition of the constituent material in the growth direction allowed to produce quantum wells with a specifically required shape of the confining potential (including parabolic, half-parabolic, triangular, and trapezoidal). Such samples were used for (i) determination of the conduction and valence band offsets in MnTe/CdTe and MgTe/CdTe systems, (ii) for the demonstration of an enhanced exciton binding in a parabolic confining potential as well as for (iii) demonstration of the possibility of "spin-splitting engineering" in diluted magnetic semiconductors quantum structures. In the second type of the structures, a precise in-plane profiling of either quantum well width or the barrier width or n-type doping intensity was realized. These structures were subsequently used for studies of the evolution of optical spectra with an increase in the concentration of confined two-dimensional gas of conduction electrons.
Źródło:
Acta Physica Polonica A; 1998, 94, 2; 199-217
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stimulated and Laser Emission in CdZnTe/CdMnTe Double Quantum Well Heterostructures
Autorzy:
Kowalczyk, L.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933829.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.45.+h
71.55.Gs
Opis:
Stimulated emission by optical excitation has been investigated in CdZnTe/CdMnTe quantum well heterostructures. Laser action has been achieved at 4.2 K and at 77 K with relatively low threshold values of the excitation intensity. Photοluminescence excitation spectra of the stimulated emission were obtained indicating that the optical gain involves exciton-exciton inelastic scattering.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 787-790
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changing the Properties of the CdTe/ZnTe Quantum Dots by in situ Annealing during the Growth
Autorzy:
Wojnar, P.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047681.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.De
78.55.Et
Opis:
We present an attempt to control the properties of CdTe/ZnTe self-assembled quantum dots during their formation in the process of molecular beam epitaxy. Namely, the structures were in situ annealed at various temperatures and annealing times after the formation of quantum dots, before the deposition of a capping layer. Depending on the annealing parameters, the dots exhibit different optical properties which were studied by means of spatially resolved photoluminescence. From the analysis of these results, the information about relative changes of the average size and sheet density of quantum dots was extracted.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 283-288
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exciton Magnetic Polaron Features in Photoluminescence Excitation Spectra of CdTe/(CdMn)Te Quantum Wells with High Mn Contents
Autorzy:
Mackh, G.
Ossau, W.
Yakovlev, D. R.
Landwehr, G.
Wojtowicz, T.
Karczewski, G.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933923.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.+z
78.55.Et
Opis:
Exciton magnetic polarons are studied in CdTe/Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te (0.4 ≤ x ≤ 0.8) quantum wells. The magnetic polaron formation leads to the appearance of an additional line in the photoluminescence excitation spectra, which can be employed to determine the Zeeman splittings more exactly than by using the free exciton peak. We find an overall increase in the polaron energy with increasing x in the whole range of Mn contents studied.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 849-852
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
δ-Doped CdTe/Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te Multiple Quantum Wells Investigated by Photoreflectance Spectroscopy
Autorzy:
Sitarek, P.
Misiewicz, J.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933972.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.Vv
78.66.Hf
Opis:
Room temperature photoreflectance spectroscopy was used to investigate CdTe/Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te multiple quantum wells grown by MBE. Structures were indium δ-doped into the well or into the barrier. The value of heavy and light hole subbands splitting was measured and compared to the calculated ones. The influence of the position of δ-doping on the measured spectra was shown.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 901-904
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Strain Relaxation of ZnTe/CdTe and CdTe/ZnTe heterostructures: In Situ Study
Autorzy:
Riesz, F.
Kret, S.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1952073.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.14.Hg
68.55.Bd
68.65.+g
Opis:
The strain relaxation kinetics of ZnTe/CdTe and CdTe/ZnTe heterostructures grown on GaAs substrates by molecular beam epitaxy are studied by in situ reflection high-energy electron diffraction. The observed critical layer thickness is 5 monolayers for ZnTe/CdTe and less than 1 monolayer for CdTe/ZnTe. The relaxation is anisotropic. Dislocation core parameters and relaxation rate constants were determined using a kinetic model and assuming strain-dependent activation energy of dislocation movement.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 911-914
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exciton Magneto-Optical Study on Single Quantum Wells, Cd$\text{}_{1-x}$Zn$\text{}_{x}$Te/Cd$\text{}_{1-x'-y}$Zn$\text{}_{x}$'Mn$\text{}_{y}$Te
Autorzy:
Takeyama, S.
Grabecki, G.
Adachi, S.
Takagi, Y.
Wojtowicz, T.
Karczewski, G.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1934045.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.-m
78.20.Ls
78.66.Hf
Opis:
Four-single quantum wells composed of the ternary non-magnetic compounds Cd$\text{}_{0.93}$Zn$\text{}_{0.07}$Te (well width = 13, 19, 40, 90 Å), separated by the quaternary magnetic-compound Cd$\text{}_{0.48}$Zn$\text{}_{0.04}$Mn$\text{}_{0.48}$Te on (100)GaAs substrate were grown by MBE, and exhibited clear and distinctive photoluminescence lines corresponding to each quantum well. Double luminescence peaks with closely spaced within one well were observed from 90 Å and 40 Å quantum wells. Temperature and magnetic-field study revealed characteristic luminescence features associated with a bound exciton near the interface rather than with one monolayer fluctuation.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 945-948
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deep Electron Traps in CdTe:In Films Grown by Molecular Beam Epitaxy
Autorzy:
Żakrzewski, A. K.
Dobaczewski, L.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1934051.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Ln
73.61.Ga
Opis:
N-type indium doped CdTe grown on n$\text{}^{+}$-GaAs by molecular beam epitaxy has been studied by the standard deep level transient spectroscopy and the isothermal Laplace-transform deep level transient spectroscopy. It was found that the Cd/Te flux ratio strongly influences the deep level transient spectroscopy results. The unusual temperature dependence of the electron emission rate in films grown at nearly stoichiometric conditions may point out that the observed defect is resonant with the conduction band.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 961-964
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:
Identification of Optical Transitions from CdTe and CdMnTe Quantum Dots Embedded in ZnTe Nanowires
Autorzy:
Szymura, M.
Kłopotowski, Ł.
Wojnar, P.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1399096.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Et
78.67.Uh
78.67.Hc
Opis:
We study photoluminescence properties of CdTe and CdMnTe quantum dots embedded in ZnTe nanowires. The nanowires were grown by molecular beam epitaxy, applying the vapor-liquid-solid growth mechanism. Linear polarization anisotropy measurements allow us to assess that the excitonic transitions originate from a single nanowire. We identify the optical transitions by comparing observed spectroscopic shifts with the universal emission pattern from the epitaxial CdTe dots. We support this identification by analyzing the photoluminescence intensity dependence on excitation power.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 824-826
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:
(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

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