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Wyszukujesz frazę "Karczewski, G" wg kryterium: Autor


Tytuł:
Doping and Characterization of Wide-Gap II-VI Epilayers
Autorzy:
Karczewski, G.
Wojtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1946648.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Ln
71.55.-i
71.55.Gs
Opis:
In this paper we review the properties of n-type doped ZnSe and CdTe epilayers grown by molecular beam epitaxy on (100) GaAs substrates. Recent results of photoluminescence, transport measurements, secondary ion mass spectroscopy and deep-level transient spectroscopy are discussed. A major emphasis is placed on the effect of different dopant species and the role of the deviation from stoichiometry on the doped epitaxial layers. Since deep defect states play an important role in determining the properties of the doped materials, considerable attention is directed towards characterization and identification of deep-lying defect states, both native and introduced by dopants. In particular, in the case of ZnSe the deep-level transient spectroscopy results clarify why Cl is superior to Ga as an effective n-type dopant. They provide strong evidence that chlorine - unlike Ga - does not introduce by itself any detectable deep defects into the ZnSe lattice. In the case of CdTe, we focus on the influence of the deviation from stoichiometric growth conditions in the molecular beam epitaxy process and on the properties of In doped layers. We discuss resistivity, Mn diffusivity and the presence of various deep defects in layers grown at different Cd/Te flux ratios.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 635-644
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diagnosing Toxoplasma gondii infection during pregnancy - a case study
Autorzy:
Karczewski, G.
Golab, E.
Powiązania:
https://bibliotekanauki.pl/articles/5842.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Parazytologiczne
Tematy:
diagnosis
human disease
Toxoplasma gondii
infection
pregnancy
toxoplasmosis
Polska
Źródło:
Annals of Parasitology; 2016, 62, Suppl.
0043-5163
Pojawia się w:
Annals of Parasitology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Studies of HgCdMnTe Bicrystals
Autorzy:
Grabecki, G.
Wróbel, J.
Karczewski, G.
Powiązania:
https://bibliotekanauki.pl/articles/1879930.pdf
Data publikacji:
1991-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
73.40.Lq
Opis:
We report preliminary results of optical measurements performed on Hg$\text{}_{1-x-k}$Cd$\text{}_{x}$Mn$\text{}_{k}$Te grain boundaries. Photovoltaic spectra and I-V characteristics under illumination exhibit metastable behavior, confirming our previous conclusions based on transport measurements under high hydrostatic pressure.
Źródło:
Acta Physica Polonica A; 1991, 79, 2-3; 221-223
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
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:
Two Charge States of Sulphur in GaSb
Autorzy:
Dobaczewski, L.
Kaczor, P.
Karczewski, G.
Poole, I.
Powiązania:
https://bibliotekanauki.pl/articles/1879480.pdf
Data publikacji:
1991-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.70.+q
78.50.Ge
71.55.Eq
Opis:
Results of the isothermal DLTS, photoconductivity, and photo-Hall measurements, showed that the sulphur-related center in GaSb, being a DX-type defect, has two charge states.
Źródło:
Acta Physica Polonica A; 1991, 79, 1; 133-136
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Single Particle and Collective Spin Excitations in Semimagnetic Quantum Wells
Autorzy:
Perez, F.
Jusserand, B.
Richards, D.
Karczewski, G.
Powiązania:
https://bibliotekanauki.pl/articles/2038315.pdf
Data publikacji:
2004-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.25.Dc
73.21.-b
75.70.-i
78.30.-j
Opis:
Collective and single-particle spin-flip excitations of a two-dimensional electron gas in a semimagnetic Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te quantum well are observed by resonant Raman scattering. Application of a magnetic field splits the spin-subbands and a spin-polarization is induced in the electron gas. Above some critical field, a collective spin-flip mode, which disperses with in-plane wave vector, dominates the spectra. The energy of this mode is given by the bare Zeeman energy at vanishing wave vector as predicted by Larmor's theorem and its in-plane dispersion is well described by a model of the interacting polarizability of a spin polarized electron gas when both exchange and correlation are taken into account.
Źródło:
Acta Physica Polonica A; 2004, 106, 3; 311-317
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultra-Fast Spin Dynamics in Diluted Magnetic Semiconductors
Autorzy:
Wilamowski, Z.
Buczko, R.
Karczewski, G.
Jantsch, W.
Powiązania:
https://bibliotekanauki.pl/articles/1952363.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.50.-y
Opis:
In nano-size antiferromagnetic systems a spatially inhomogeneous field leads to the formation of a staggered magnetization. Thereby the total magnetic moment does not change but the formation of a net magnetic moment at the border of the cluster leads to an energy gain. This type of magnetism is characterised by an ultra-fast dynamics. We suggest it is also responsible for the formation of the exciton magnetic polaron.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 969-972
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrical Properties of p-ZnTe/n-CdTe Photodiodes
Autorzy:
Chusnutdinow, S.
Makhniy, V.
Wojtowicz, T.
Karczewski, G.
Powiązania:
https://bibliotekanauki.pl/articles/1409588.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Hi
73.61.Ga
85.60.Dw
88.40.jm
Opis:
Current-voltage (I-V) and capacitance-voltage (C-V) characteristics of photovoltaic, thinfilm p-ZnTe/n-CdTe heterojunctions have been studied in the temperature range of 280-400 K. The p-n junctions were grown by MBE on (100) semi-insulating GaAs substrates. From the analysis of I-V and C-V curves the potential barrier height of the junctions and its temperature dependence are determined. The relatively large value of the temperature coefficient of the potential barrier height (2.5-3.0 × $10^{-3}$ eV/K) indicates a high density of defects at the p-ZnTe/n-CdTe interface. The presence of interface defects limits the efficiency of the solar energy conversion of these devices.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1077-1079
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:
Ferroelectric Field Effect Transistor Based on Modulation Doped CdTe/CdMgTe Quantum Wells
Autorzy:
Kolkovsky, V.
Wojciechowski, T.
Wojtowicz, T.
Karczewski, G.
Powiązania:
https://bibliotekanauki.pl/articles/1811945.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.80.-e
77.80.Fm
85.50.Gk
73.61.Ga
Opis:
In this work, we observed effects of changing the electron concentration and electron mobility upon the poling of the $Cd_{0.96}Zn_{0.04}Te$ ferroelectric gate deposited on the top of the CdTe-based modulation doped quantum well structure, which are confirmation of the existence of the electrostatic field originating from the ferroelectric material, which can be controlled by an external voltage. The analysis of the data obtained from the Hall effect measurements showed that the electron mobility and carrier concentration decreased by a factor of 2.5 and 1.5, respectively upon the negative poling of the gate with respect to the poled by the positive voltage. Moreover, the electrostatic field, depending on its directions, causes depletion of accumulation of electrons in the 2D channel, i.e., it is a source of the field effect.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1173-1178
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Relaxation Processes in Quantum Well Structures of Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te/Cd$\text{}_{1-x}$Mg$\text{}_{x}$Te
Autorzy:
Khachapuridze, A.
Ivanov, V. Yu.
Godlewski, M.
Karczewski, G.
Powiązania:
https://bibliotekanauki.pl/articles/2035595.pdf
Data publikacji:
2002
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.Ji
72.25.Rb
76.70.Hb
78.55.Et
Opis:
Fast spin relaxation of Mn$\text{}^{2+}$ ions in a magnetic quantum well of CdMnTe with 1% Mn fraction is related to a very efficient spin-flip interaction between Mn ions and free carriers. This mechanism of spin relaxation becomes dominant at increased excitation densities. The observed response of the photoluminescence bands to the Mn$\text{}^{2+}$ magnetic resonance indicates that free carriers are heated at the magnetic resonance conditions. A decrease in formation/recombination rates of free and trion excitons is observed. Donor bound exciton photoluminescence is enhanced, which we relate to delocalization of free excitons, caused by interaction with microwave heated free carriers.
Źródło:
Acta Physica Polonica A; 2002, 102, 4-5; 643-648
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:
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

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