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Tytuł:
Intraday patterns in time-varying correlations among Central European stock markets
Autorzy:
Wójtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/108424.pdf
Data publikacji:
2016
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
CEE stock markets
DCC-GARCH model
emerging markets
intraday data
Opis:
In this paper we investigate intraday relationships between three Central European stock exchanges: those in Frankfurt, Vienna and Warsaw. They represent different types of stock markets: two of them are developed, while the last is an emerging market. Via DCC-GARCH models we analyze and compare time-varying conditional correlations of intraday returns of the main indices of the stock exchanges. We study the impact of important public information, US macroeconomic news announcements, on the strength of interrelationships between the markets. Additionally, we analyze diurnal patterns in time-varying correlations on different days of the week.
Źródło:
Managerial Economics; 2016, 17, 1; 149-162
1898-1143
Pojawia się w:
Managerial Economics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zabezpieczenie medyczne nurkowań głębokich realizowanych przez OOR 281, 282 w latach 1993–1996
Medical security of deep dives realized by OOR 281 and 282 in the years 1993–1996
Autorzy:
Wojtowicz, T
Powiązania:
https://bibliotekanauki.pl/articles/366668.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Medycyny i Techniki Hiperbarycznej
Tematy:
nurkowanie
prace podwodne
mieszaniny oddechowe
trymiks
aparaty o obiegu półzamkniętym
rekompresja lecznicza
diving
underwater works
breathing mixes
trimix
semi-closed rebreathers
medical recompression
Opis:
Celem pracy było przedstawienie rozwiązań technicznych i medycznych, zastosowanych podczas pierwszych polskich roboczych nurkowań na średnie głębokości z użyciem trymiksu jako czynnika oddechowego. Praca zawiera analizę całokształtu działań medycznych – profilaktycznych, diagnostycznych i leczniczych, stosowanych podczas trwania 4-letniego przedsięwzięcia.
The aim of the work was to present technical and medical solutions applied in the first Polish working dives at average depths with the use of trimix as a breathing mixture. The article encompasses an analysis of the entirety of the performed medical activities – the preventive, diagnostic and therapeutic measures applied in the course of a 4-year-long undertaking.
Źródło:
Polish Hyperbaric Research; 2013, 1(42); 27-55
1734-7009
2084-0535
Pojawia się w:
Polish Hyperbaric Research
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
The reaction of the WSE to U.S. employment news announcements
Reakcja GPW w Warszawie na ogłoszenia danych o zatrudnieniu w USA
Autorzy:
Suliga, M.
Wójtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/108319.pdf
Data publikacji:
2013
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
event study
macroeconomic announcements
unemployment
nonfarm payrolls
analiza zdarzeń
ogłoszenia danych makroekonomicznych
bezrobocie
zatrudnienie w sektorze pozarolniczym
Opis:
Stock markets react to various information. One of the most important information concerns macroeconomic data because it describes the state of the economy. The U.S. is the world’s largest economy and thus American macroeconomic news announcements strongly affects European stock markets. In this paper we investigate the reaction of stock prices on the Warsaw Stock Exchange to values of macroeconomic indicators published in the Employment Report by the U.S. Bureau of Labor Statistics. We study the impact of macroeconomic indicators separately as well as interrelations between them. It allows us to specify which of the indicators under study is the most informative. We analyze the impact of information about the state of the labor market in the U.S. in the period from January 2004 to November 2012. In order to describe duration, direction and significance of the impact we apply the event study analysis to intraday returns of WIG – the main index of WSE.
Rynki akcji reagują na różnego rodzaju napływające informacje. Najważniejsze z nich dotyczą danych makroekonomicznych, gdyż opisują one stan całej gospodarki. Ponieważ USA stanowią największą gospodarkę na świecie, to ogłoszenia amerykańskich danych makroekonomicznych szczególnie silnie wpływają na europejskie rynki akcji. W tym artykule zbadano reakcje cen akcji notowanych na Giełdzie Papierów Wartościowych w Warszawie na wartości wskaźników makroekonomicznych publikowanych przez Bureau of Labor Statistics w Raporcie o zatrudnieniu. Badano wpływ każdego ze wskaźników z osobna oraz wzajemne relacje pomiędzy wskaźnikami. To pozwoli na określenie, który spośród rozważanych wskaźników jest najważniejszy. W artykule badano wpływ informacji o sytuacji na amerykańskim rynku pracy w okresie od stycznia 2004 do listopada 2012. Aby określić czas reakcji GPW na napływające informacje, kierunek tej reakcji oraz jej istotność, zastosowano analizę zdarzeń dla śróddziennych stóp zwrotu indeksu WIG.
Źródło:
Managerial Economics; 2013, 14; 165-176
1898-1143
Pojawia się w:
Managerial Economics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial contagion between stock markets in Central Europe
Autorzy:
Czapkiewicz, A.
Wójtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/108342.pdf
Data publikacji:
2017
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
contagion
CEE markets
risk management
tail dependence
copula function
Opis:
In this paper, we investigate contagion between three European stock markets: those in Frankfurt, Vienna, and Warsaw. Two of them are developed markets, while the last is an emerging market. Additionally, the stock exchanges in Vienna and Warsaw are competing markets in the CEE region. On the basis of daily and intraday returns, we analyze and compare the dependence between the major indices of these markets during calm and turbulent periods. A comparison of the dependence in the tail and in the central part of the joint distribution of returns (via a spatial contagion measure) indicates strong contagion among the analyzed markets. Additionally, the application of a conditional contagion measure indicates the importance of taking into account the situation on other markets when contagion between two markets is considered.
Źródło:
Managerial Economics; 2017, 18, 1; 23-45
1898-1143
Pojawia się w:
Managerial Economics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi-domain battle : new doctrine of the United States Armed Forces
Autorzy:
Wójtowicz, T.
Król, D.
Powiązania:
https://bibliotekanauki.pl/articles/93320.pdf
Data publikacji:
2018
Wydawca:
Akademia Sztuki Wojennej
Tematy:
multi-domain battle
operational principles
military doctrines
US Armed Forces
Opis:
This article describes the newest doctrine of the U.S. Armed Forces, i.e. the Multi- Domain Battle (MDB) concept. It constitutes a description of several operational principles related to a potential conflict with the People’s Republic of China or the Russian Federation, such as the time and space for conducting military operations, the operating environment, the forces (base of operations), the target, the concentration of forces and the operational leeway. The article looks at the origins of the doctrine, the circumstances under which it was formed and people who contributed to its development. The authors also refer to historical U.S. doctrines, such as the AirLand Battle or AirSea Battle concepts. Along with the authors’ enthusiastic approach to MDB, the article also features some critical opinions which imply that the U.S. Army is not ready for MDB operations. The research methods that were used by the authors included analysis, synthesis, comparison and generalisation. Much space is devoted to analysing the U.S. Army’s official documents, including Multi-Domain Battle: Evolution of Combined Arms for the 21st Century 2025-2040, FM 3-0 Operations and TRADOC Multi-Domain Battle: Combined Arms for the 21st Century. The authors believe that Multi-Domain Battle is about to become the official military doctrine of the U.S. Armed Forces. In spite of the criticism, transformations of individual combat teams in the MDB spirit should be expected in the upcoming years. This doctrine also provides a military response to the geo-political changes occurring in the world, manifested as the United State’s limited role in certain regions, China’s growing power and Russia’s aggressive foreign policy. The conclusions formulated in the article may serve as the starting point for further studies dealing, inter alia, with the Polish Army’s readiness for conducting military operations, based on the MDB doctrine, jointly with the U.S. Army, the Polish Anti-Access/Area Denial (A2AD) capabilities and the role of military technologies in the MDB doctrine. The article makes use of the exact translation of the term, i.e. “Multi-Domain Battle.” However, the reader should bear in mind that it describes capabilities not only at the tactical level but also in operational terms, enabling the accomplishment of the strategic objective.
Źródło:
Zeszyty Naukowe Akademii Sztuki Wojennej; 2018, 3(112); 64-78
2543-6937
Pojawia się w:
Zeszyty Naukowe Akademii Sztuki Wojennej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wpływ stopnia dojrzałości wiech na wartość siewną nasion Festuca pratensis
Effect of degree of panicle maturity on sowing value of Festuca pratensis seeds
Autorzy:
Wojtowicz, T.
Mos, M.
Powiązania:
https://bibliotekanauki.pl/articles/75644.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Łąkarskie
Opis:
The aim of this study conducted in the years 2006–2008 was to evaluate the effect of harvest date and varietal variation on sowing value of seeds threshed and shattered from panicles with different degree of maturity in four meadow fescue cultivars. Germinability as well as weight of 1000 seeds were strongly affected by varietal factor and interaction of this factor with harvest date in successive years. Seeds threshed from panicles in the third degree of maturity were characterized by high germinability (84%) but the highest value of this index (87%) was estimated for seeds obtained during induced shattering, notwithstanding the lowest weight of 1000 shattered seeds (2.115 g). Inconsiderable variation of germinability of threshed seeds between applied dates of harvest in analyzed three-year period points to the possibility of harvesting at the earlier date to reduce losses in seed yield caused by shattering process.
Źródło:
Łąkarstwo w Polsce; 2011, 14
1506-5162
Pojawia się w:
Łąkarstwo w Polsce
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of Russian military involvement in the war in Syria
Autorzy:
Wójtowicz, T.
Barsznica, I.
Drąg, K.
Powiązania:
https://bibliotekanauki.pl/articles/93241.pdf
Data publikacji:
2018
Wydawca:
Akademia Sztuki Wojennej
Tematy:
Russia
military intervention
war in Syria
Rosja
interwencja wojskowa
wojna w Syrii
Opis:
The Russian military intervention in Syria, conducted between September 2015 and March 2016, was one of the crucial moments in the Middle East conflict which has evolved since 2011. It not only prevented the collapse of the regime of Bashar al-Assad but also enabled the initiative to be taken by the Syrian Arab Army. The simultaneous conducting of two military operations by the Russian army, i.e. the Russian involvement in both Ukraine and the Middle East, requires thorough investigations into the course of these operations. Such investigations may provide answers to a number of questions which appear of key importance to Poland, e.g., regarding Russia’s logistic and technological abilities to conduct military operations outside its territory, the military outcomes of the Russian intervention, and the potential social opposition to the human losses sustained by Russia as a result of such interventions. Considering the above, the aim of this article is to outline the Russian military intervention in Syria, and its influence on the course of the war. Special attention was paid to such issues as the causes behind the Russian intervention, the situation on the Syrian war frontlines prior to this intervention, the Russian forces engaged and the resources intended for this military operation, as well as its outcome.
Źródło:
Zeszyty Naukowe Akademii Sztuki Wojennej; 2018, 2(111); 85-99
2543-6937
Pojawia się w:
Zeszyty Naukowe Akademii Sztuki Wojennej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Próba zastosowania komputerowej analizy obrazu w ocenie imbibicji i wigoru ziarna pszenżyta jarego
The use of a computer-aided image analysis to estimate the imbibition and vigour of spring triticale seeds
Autorzy:
Mos, M.
Wiwart, M.
Wojtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/804671.pdf
Data publikacji:
2002
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Opis:
Badano proces imbibicji ziarniaków pszenżyta jarego odmiany Gabo przechowywanych uprzednio przez rok, dwa i trzy lata. W ciągu 14 godzin imbibicji dokonywano pomiarów masy oraz powierzchni, obwodu, długości i szerokosci rzutu obrazu ziarniaków. Dodatkowo wykonano jeszcze takie same pomiary w 24 i 26 godzinie pęcznienia. Uzyskane wyniki świadczą o bardzo silnej korelacji między masą pęczniejących ziarniaków a cechami geometrycznymi ich obrazu, zwłaszcza powierzchnią. Wskazuje to na możliwość zastosowania cyfrowej analizy obrazu w badaniach imbibicji ziarna zbóż.
The process of imbibition of spring triticale seeds, cv. Gabo, after storage for one, two and three years, was investigated. During 14 hours of imbibition, measurements of the weight of seeds, as well as the measurements of the circumference, length and width of the seed projection were taken. In addition, the same measurements were taken in the 24th and 26th hour of imbibition. The results obtained point to a very strong correlation between the mass of the imbibing seeds and the geometrical characteristics of their projection, especially the area. This indicates the possibility of applying the computer-aided image analysis for the estimation of cereal seeds imbibition.
Źródło:
Zeszyty Problemowe Postępów Nauk Rolniczych; 2002, 488, 1
0084-5477
Pojawia się w:
Zeszyty Problemowe Postępów Nauk Rolniczych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Linear and nonlinear intraday causalities in response to U.S. macroeconomic news announcements: Evidence from Central Europe
Autorzy:
Gurgul, H.
Lach, Ł.
Wójtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/108370.pdf
Data publikacji:
2016
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
trading volume
return volatility
public news
sequential information arrival
Granger causality
Opis:
This paper deals with an analysis of the information flow on and between three European stock markets operating in Frankfurt, Vienna, and Warsaw. We examine causal links between returns, volatility, and trading volume as well as the time of reaction to a news release and changes in the duration of causal interference. To model the conditional variance, we use the ARMA(1,1)- EGARCH-M(1,1) model. We investigate linear and nonlinear Granger causalities on the three stock exchanges using Bayesian large sample correction of the critical values in significance tests. The results of our study confirm the dominant role of the Frankfurt Stock Exchange, since the most significant linear relationship is the causality running from DAX30 returns to the returns of the ATX20 and WIG20 (which exists irrespective of the time of the day, presence of important public news, and lag length of the underlying VAR models). Moreover, the empirical results of this paper confirm the strong impact of announcements of macroeconomic news from the U.S. economy on the structure of both linear and nonlinear causal links on the three markets under study
Źródło:
Managerial Economics; 2016, 17, 2; 217-240
1898-1143
Pojawia się w:
Managerial Economics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Correlations and path analysis of the components of Festuca pratensis seed yield
Korelacje i analiza ścieżek komponentów plonu nasion Festuca pratensis
Autorzy:
Wojtowicz, T.
Binek, A.
Mos, M.
Powiązania:
https://bibliotekanauki.pl/articles/75962.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Łąkarskie
Tematy:
correlation
path analysis
yield component
Festuca pratensis
meadow fescue
plant cultivar
seed yield
yield
Opis:
Seed yield and yield components were investigated using single meadow fescue plants (Festuca pratensis Huds.) grown in widely spaced rows. Plants of four cultivars (Cykada, Skawa, Skiba and Skra), entered into the EU catalogue, made the representative sample. On the basis of observations and measurements of 20 plants from two harvest dates and three vegetation seasons, the number of days till heading, number of panicles, seed weight per panicle, degree of panicle axis maturity, weight of fallen seeds, the shedding being induced under laboratory conditions, and gross seed yield. For these traits mean values, coefficients of variation, simple correlation coefficients and Wright’s path coefficients were calculated. Over the period of the three-year experiments the greatest variation was found for seed weight per panicle, seed yield per plant and number of panicles, especially in the first harvest year. From among the investigated traits, seed yield per plant was most correlated with the number of panicles per plant (r = 0.480** to r = 0.829**) and seed weight per panicle (r = 0.336* to r = 0.820**). As the number of panicles per plant increased, the weight of fallen seeds increased as well (r = 0.432** to r = 0.620**). The path analysis confirmed the finding that the number of panicles per plant, increasing in successive years, determined the seed yield by 12–23%, 40–46% and 63–74% respectively. The greatest direct effects of the number of panicles and seed weight per panicle on seed yield were observed in the second harvest year.
Plon nasion i komponenty plonu badano na pojedynczych roślinach kostrzewy łąkowej wysadzonych w szerokiej rozstawie. Próbę reprezentatywną stanowiły rośliny 4 odmian (Cykada, Skawa, Skiba i Skra) wpisanych do katalogu UE. Na podstawie obserwacji i pomiarów 20 roślin z dwóch terminów zbioru i trzech lat wegetacji roślin określono liczbę dni do kłoszenia, liczbę wiech, masę nasion/wiechę, stopień dojrzałości osadek wiechy, masę nasion osypanych indukowaną w warunkach laboratoryjnych oraz plon nasion brutto. Dla wymienionych cech obliczono wartości średnie, współczynniki zmienności, proste współczynniki korelacji oraz współczynniki ścieżek Wrighta. W okresie trzech lat doświadczeń największą zmienność wykazała masa nasion z wiechy, plon nasion z rośliny oraz liczba wiech zwłaszcza w pierwszym roku zbioru nasion. Spośród badanych cech plon nasion z rośliny był najsilniej skorelowany z liczbą wiech na roślinie (r = 0,480** do r = 0,829**) oraz masą nasion z wiechy (r = 0,336* do r = 0,820**). Ze wzrostem liczby wiech na roślinie zwiększała się masa nasion osypanych (r = 0,432** do r = 0,620**). Analiza ścieżek potwierdziła, że zwiększająca się w kolejnych latach wegetacji liczba wiech na roślinie determinowała plon nasion odpowiednio w 12–23%, 40–46% oraz 63–74% w trzecim roku zbioru kostrzewy łąkowej. Największy bezpośredni wpływ liczby wiech i masy nasion z wiechy na plon nasion obserwowano w drugim roku zbioru nasion. Negatywny trend pośredniego wpływu wykazała masa nasion poprzez liczbę wiech na plon nasion. Pozytywny pośredni wpływ masy nasion poprzez liczbę wiech na plon nasion ujawnił się w trzecim roku zbioru i wskazuje, że wraz z zwiększeniem liczby wiech na roślinie zwiększa się nierównomierne ich dojrzewanie powodujące większą skłonność do osypywania nasion.
Źródło:
Łąkarstwo w Polsce; 2009, 12
1506-5162
Pojawia się w:
Łąkarstwo w Polsce
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of morpho-anatomical stem properties determining its mechanical strength in selected rye cultivars
Autorzy:
Wójtowicz, T.
Grabowska-Joachimiak, A.
Zieliński, A.
Powiązania:
https://bibliotekanauki.pl/articles/2082669.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
Secale cereale
biodegradable straws
mechanical
properties
failure moment (Bs)
stem anatomy
Opis:
The objective of the research was to compare important properties of the morphological and anatomical structure of stems of four open-pollinated rye cultivars in relation to their mechanical strength expressed by the failure moment, taking into account the possibility of using the stems for the manufacture of natural drinking straws. From the 2nd and the 3rd stem internodes, cross sections were obtained within which the number of large vascular bundles, the diameters of the stem and the central canal, as well as the thicknesses of the stem wall, sclerenchyma and parenchyma were determined. The differentiation in cultivar properties was mainly affected by the location of the internode within the stem. The stem diameter ranged from 5.2 mm (Dańkowskie Rubin) to 5.4 mm (Antonińskie). As compared with the 3rd internode, in the 2nd internode the values of the analysed traits ranged from 5 to 25% higher. In both internodes a significant correlation (r>0.680, p<0.01) between the stem diameter and the central canal diameter was found. In all the cultivars the failure moment depended significantly on the stem diameter for both the internodes (r > 0.638, p < 0.01). The analyses carried out show that the 2nd internode is characterized by the most favourable properties affecting the mechanical strength of rye stems.
Źródło:
International Agrophysics; 2020, 34, 1; 123-131
0236-8722
Pojawia się w:
International Agrophysics
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:
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:
Vigour of naked and husked oat cultivars under drought stress conditions
Autorzy:
Zielinski, A.
Simlat, M.
Wojtowicz, T.
Mos, M.
Powiązania:
https://bibliotekanauki.pl/articles/80585.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
seed vigor
husked oat
naked oat
oat cultivar
drought stress
water stress
thermal condition
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 3
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
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:
Application of Photomemory Effect in Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$:In for Direct Measurements of Magnetization of Bound Magnetic Polarons
Autorzy:
Wojtowicz, T.
Koleśnik, S.
Miotkowski, I.
Furdyna, J. K.
Powiązania:
https://bibliotekanauki.pl/articles/1921550.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.38.+i
75.50.Pp
Opis:
The first direct measurement of the magnetization of donor bound magnetic polarons in diluted magnetic semiconductors is reported. The experiment has been performed taking advantage of photomemory effect found in n-type Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$ crystals doped with In. Good agreement between experimental results and theory of bound magnetic polarons is observed.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 637-640
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
Tytuł:
Time-Resolved Studies of Excitonic Dynamics in a Wide II-VI Quantum Well by a Femtosecond Pump-Probe Reflectivity
Autorzy:
Trajnerowicz, A.
Golnik, A.
Kossacki, P.
Pacuski, W.
Wojtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/2047018.pdf
Data publikacji:
2006-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.De
71.35.Pq
78.47.+p
Opis:
We present time-dependent reflectance spectra of wide (Cd,Mn)Te/(Cd,Mg)Te quantum wells. Interactions between excitons, trions, and carriers are studied for exciton densities up to 10$\text{}^{11}$ cm$\text{}^{-2}$. The resonant excitation at different excitonic lines is analyzed.
Źródło:
Acta Physica Polonica A; 2006, 110, 3; 395-401
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Light-Controlled Transport in Doped Diluted Magnetic Semiconductors near Localization Boundary
Autorzy:
Głód, P.
Dietl, T.
Wojtowicz, T.
Sawicki, M.
Miotkowski, I.
Powiązania:
https://bibliotekanauki.pl/articles/1929694.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.30.+h
75.50.Pp
72.40.+w
Opis:
We report milikelvin studies of light induced metastable changes of the conductivity of the In doped Cd$\text{}_{0.95}$Mn$\text{}_{0.05}$Te$\text{}_{0.97}$Se$\text{}_{0.03}$ crystals in the vicinity of the metal-insulator transition.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 657-660
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:
Photoluminescence of CdTe/CdMgTe Double Quantum Wells with a Two-Dimensional Electron Gas
Autorzy:
Deresz, M.
Wiater, M.
Karczewski, G.
Wojtowicz, T.
Łusakowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1033223.pdf
Data publikacji:
2017-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
CdTe/CdMgTe quantum wells
magnetophotoluminescence
Opis:
Magnetophotoluminescence measurements at liquid helium temperatures were carried out on asymmetric double quantum wells based on CdTe/CdMgTe heterostructures. Due to doping with shallow iodine donors, a two-dimensional electron gas was present in the quantum wells. The samples studied differed with the quantum well widths and doping level. We show a resemblance of the luminescence to results obtained on single quantum wells which suggests that in samples studied the quantum wells are not strongly coupled.
Źródło:
Acta Physica Polonica A; 2017, 132, 2; 390-392
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rare Earth Ion Implantation in GaN: Damage Formation and Recovery
Autorzy:
Gloux, F.
Ruterana, P.
Wojtowicz, T.
Lorenz, K.
Alves, E.
Powiązania:
https://bibliotekanauki.pl/articles/2046897.pdf
Data publikacji:
2006-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.Vv
61.72.Nn
68.37.Lp
81.05.-t
Opis:
Rare earth ions implanted GaN has been investigated by transmission electron microscopy versus the fluence, using Er, Eu or Tm ions at 150 keV or 300 keV and at room temperature. Point defect clusters and stacking faults are generated from low fluences (7×10$\text{}^{13}$ at/cm$\text{}^{2}$), their density increases with the fluence up to the formation of a highly disordered layer at the surface. This highly disordered layer is observed from a threshold fluence of 3×10$\text{}^{14}$ at/cm$\text{}^{2}$ at 150 keV and 3×10$\text{}^{15}$ at/cm$\text{}^{2}$ at 300 keV, and appears to be composed of voids and misoriented nanocrystallites. Its thickness rapidly increases with the fluence, and then saturates. Both basal and prismatic stacking faults were observed. Basal stacking faults are I$\text{}_{1}$ in majority, but E or I$\text{}_{2}$ have also been identified. I$\text{}_{1}$ basal stacking faults propagate easily through GaN by folding from basal to prismatic planes. Channelling implantation, increasing the implantation temperature from room temperature to 500ºC, or implanting through a 10 nm thick AlN cap reduce the crystallographic damage, particularly by retarding the formation of the highly disordered layer. Implanting through the AlN cap allows the highly disordered layer formation threshold fluence to be increased by one order of magnitude, as well as the annealing at high temperature (1300ºC) which brings about a strong optical activation of the rare earths.
Źródło:
Acta Physica Polonica A; 2006, 110, 2; 125-137
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:
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:
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:
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:
Mechanical and Electrical Properties, of ZnO-Nanowire/Si-Substrate Junctions Studied by Scanning Probe Microscopy
Autorzy:
Aleszkiewicz, M.
Fronc, K.
Wróbel, J.
Klepka, M.
Wojtowicz, T.
Karczewski, G.
Powiązania:
https://bibliotekanauki.pl/articles/2047440.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.37.Ef
68.37.Ps
68.65.La
73.21.Hb
78.67.Lt
Opis:
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.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 255-260
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Search for Dimensionality Crossover of Spin-Glass Freezing in Superlattices of Cd$\text{}_{0.50}$Mn$\text{}_{0.50}$Te/CdTe
Autorzy:
Sawicki, M.
Dietl, T.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Skośkiewicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1952078.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
75.50.Rr
75.50.Lk
Opis:
SQUID measurements of the time decay of the thermoremanent magnetization (field-cooled in 1000 Oe) at long time scale, 10$\text{}^{2}$ < t < 10$\text{}^{5}$ s, are presented for MBE grown Cd$\text{}_{0.50}$Mn$\text{}_{0.50}$Te. We found that for both thin (32 Å) and thick (2500 Å) layers the spin-glass dynamics is characterized by a similar value of k = -(1/T$\text{}_{f}$)(dT$\text{}_{f}$/dlogt) > 0.05, indicating the absence of the phase transition at nonzero temperature under the experimental conditions.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 919-922
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Mobility 2D Electron Gas in CdTe/CdMgTe Heterostructures
Autorzy:
Karczewski, G.
Jaroszyński, J.
Kutrowski, M.
Barcz, A.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1968126.pdf
Data publikacji:
1997-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Hm
Opis:
We report on iodine doping of molecular beam epitaxy (MBE)-grown Cd(Mn)Te quasi-bulk films and modulation-doped CdTe/Cd$\text{}_{1-y}$Mg$\text{}_{y}$Te two-dimensional (2D) single quantum well structures. Modulation doping with iodine of CdTe/Cd$\text{}_{1-y}$Mg$\text{}_{y}$Te structures resulted in fabrication of a 2D electron gas with mobility exceeding 10$\text{}^{5}$ cm$\text{}^{2}$/(V s). This is the highest mobility reported in wide-gap II-VI materials.
Źródło:
Acta Physica Polonica A; 1997, 92, 4; 829-832
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recombination Processes in Doped CdTe/CdMnTe Multiple Quantum Well Structures Grown by Molecular Beam Epitaxy
Autorzy:
Godlewski, M.
Wojtowicz, T.
Karczewski, G.
Kossut, J.
Bergman, J. P.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1968089.pdf
Data publikacji:
1997-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.47.+p
78.55.Et
Opis:
An influence of doping level on exciton properties in n-doped multiple quantum well structures of CdTe/CdMnTe is studied for multiple quantum well structures prepared in the way that donor (indium) concentration changes within the length of the sample. We show that the formation scenario for neutral donor bound excitons in low-dimensional structures can be different from that observed in bulk samples. We further show that in the case of such quantum well structures we can selectively excite either photoluminescence emission of localized or donor bound excitons, which is a consequence of surprisingly weak energy transfer link between two types of excitonic transitions.
Źródło:
Acta Physica Polonica A; 1997, 92, 4; 757-760
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Persistent Spin Resonance of Donor Electrons and Hopping Magnetoconductivity in Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$
Autorzy:
Wojtowicz, T.
Semaltianos, N.
Kłosowski, P.
Dobrowolska, M.
Furdyna, J. K.
Miotkowski, I.
Powiązania:
https://bibliotekanauki.pl/articles/1890647.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Ls
71.25.Jd
72.20.My
Opis:
The first observation of electric dipole spin resonance of donor electrons in Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$ in far-infrared magnetotransmission is reported. Modification of the donor wave function due to non-diagonal exchange interaction with localized magnetic moments and to magnetic fluctuations are believed to allow this resonance. Hopping magnetoconductivity studied in the same crystals shows a behavior typical for wide gap diluted magnetic semiconductors.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 287-290
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exciton Dynamics in ZnTe Based Semimagnetic Semiconductors and CdMnTe Quantum Wells
Autorzy:
The Khoi, Nguyen
Gaj, J.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Demianiuk, M.
Powiązania:
https://bibliotekanauki.pl/articles/1952068.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
78.66.Hf
73.20.Dx
Opis:
Inelastic scattering of excitons on LO phonons in ZnTe based bulk semimagnetic semiconductors with low concentration of paramagnetic ions (Mn$\text{}^{2+}$, Fe$\text{}^{2+}$ and Cr$\text{}^{2+}$) was studied. A polarization degree of the LO phonon Raman lines was measured as a function of the exciton splitting in a magnetic field, and allowed us to determine the polarization lifetime (polariton flight time). A similar method was used to investigate multiple Mn$\text{}^{2+}$ spin-flip scattering in CdMnTe quantum well. The cascade model seems to be not adequate to interpret the dependence of the polarization degree on the order of scattering.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 899-902
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low Temperature Processing of Nanostructures Based on II-VI Semiconductors Quantum Wells
Autorzy:
Majewicz, M.
Śnieżek, D.
Wojciechowski, T.
Baran, E.
Nowicki, P.
Wojtowicz, T.
Wróbel, J.
Powiązania:
https://bibliotekanauki.pl/articles/1376129.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ga
73.63.Hs
68.37.Hk
62.23.St
Opis:
We report the first results of electron beam lithography processes performed on polymethyl methacrylate (PMMA) and hydrogen silsesquioxane (HSQ) resists, which have been pre-backed in vacuum at T ≤ 90°C. For such low temperature processing the lithographical resolution is reduced as compared to standard procedures, however, the exposure contrast and adhesion to CdTe and HgTe substrates have been sufficient for the fabrication of sub-μ m quantum devices. Furthermore, the new method of electrical microcontact forming is proposed, based on the local melting and annealing of an indium metal layer, performed with the application of accelerated electron beam. The method has been tested for CdTe/CdMgTe quantum wells using the lithography techniques, the exposure parameters have been optimized by inspecting the morphology of annealed metal film via the in situ imaging.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1174-1176
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Morphometric study on the lesions in the trachea wall in rats in hyperbaric oxygen therapy
Badania morfometryczne zmian w ścianie oskrzeli u szczurów w hiperbarii tlenowej
Autorzy:
Siermontowski, P.
Konarski, M.
Pedrycz, A.
Wojtowicz, T
Ostapowicz van Damme, K.
Kulig, M.
Powiązania:
https://bibliotekanauki.pl/articles/366428.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Medycyny i Techniki Hiperbarycznej
Tematy:
oxygen
hyperbaria
morphometrics
trachea
tlen
hiperbaria
morfometria
tchawica
Opis:
Clinical observations and experimental research results prove the toxic effect of oxygen on the respiratory tract both in normo- and hyperbaria. The majority of available studies concern changes in the lung parenchyma, only some of them refer to the impact of hyperbaric oxygen on the respiratory tract. The objective of the study based on an animal model was to provide an evaluation of the effect of overpressure of exhaled oxygen (oxygen hyperbaria) and the time of its duration on morphological changes in the mucous and submucous membranes of the trachea. Oxygen hyperbaria corresponding to the depth of 5 – 7 metres induces temporary motor agitation and increased aggression in rats lasting from 3 to 20 minutes. Further rises of oxygen pressure cause a reduction of the agitation, whereas at the depth of 40 m it results in extreme weakening of the breathing activity and leads to the animals’ death.Growing oxygen hyperbaria causes thickening of both the mucous and submucous membranes of the rats’ trachea accompanied by narrowing of its lumen. The changes are intensified with prolonged duration of hyperbaric oxygen therapy. The most serious morphological changes were observed in the submucous membrane of the trachea. The dominant lesion consisted of an interstitial oedema with the widening of the vascular bed. Progressing hyperbaria caused thickening of the mucous and submucous membranes with a simultaneous reduction of the trachea lumen. Similar tendencies persisted with prolonged duration of hyperbaria.
Obserwacje kliniczne oraz wyniki badań doświadczalnych dowodzą toksycznego działania tlenu na drogi oddechowe zarówno w normo - jak i hiperbarii. Większość dotychczasowych opracowań dotyczy zmian w miąższu płucnym, tylko pojedyncze odnoszą się do wpływu hiperbarii tlenowej na drogi oddechowe. Celem badań własnych na modelu zwierzęcym, była ocena wpływu nadciśnienia tlenu wdychanego (hiperbarii tlenowej) i czasu stosowania tego nadciśnienia na zmiany morfologiczne w błonie śluzowej i włóknistej tchawicy. Hiperbaria tlenowa odpowiadająca głębokości do 5 - 7 metrów wywołuje u szczurów przejściowe, trwające od 3 do 20 minut pobudzenie ruchowe i zwiększenie agresywności. Dalsze zwiększanie ciśnienia tlenu powoduje zmniejszenie ich ruchliwości, a na głębokości do 40 m doprowadza do ekstremalnego osłabienia oddychania i padania zwierząt. Narastanie hiperbarii tlenowej powoduje u szczurów pogrubienie zarówno błony śluzowej jak i włóknistej tchawicy, przy równoczesnym zwężeniu jej światła. Zmiany te narastają wraz z wydłużaniem czasu działania hiperbarii tlenowej. Wśród tych zmian dominował obrzęk śródmiąższowy z poszerzeniem łożyska naczyniowego. W miarę narastania hiperbarii obserwowano pogrubienie błony śluzowej i włóknistej, przy równoczesnym zmniejszaniu się światła tchawicy. Podobne tendencje utrzymywały się wraz z narastaniem czasu działania hiperbarii.
Źródło:
Polish Hyperbaric Research; 2013, 2(43); 7-22
1734-7009
2084-0535
Pojawia się w:
Polish Hyperbaric Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization Dynamics of a (Cd,Mn)Te Quantum Well in Pulsed Magnetic Field
Autorzy:
Kobak, J.
Goryca, M.
Kossacki, P.
Golnik, A.
Karczewski, G.
Wojtowicz, T.
Gaj, J.
Powiązania:
https://bibliotekanauki.pl/articles/1791344.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.Hc
71.70.Gm
78.55.Et
75.75.-c
Opis:
In this paper we present studies of magnetization relaxation in a (Cd,Mn)Te quantum well containing 3.2% of Mn, after a pulse of magnetic field. The relaxation was found to be very fast, with dominant component faster than 10 ns. Upon application of static magnetic field the relaxation does not slow down, in contrast with the behavior of very diluted quantum wells or bulk material.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 907-908
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cold and Hot Excitons in CdMnTe/CdMgTe Quantum Wells in Strong Excitation Regime and External Magnetic Field
Autorzy:
Trajnerowicz, A.
Golnik, A.
Kossacki, P.
Bardyszewski, W.
Wiater, M.
Karczewski, G.
Wojtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1791298.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.De
71.35.Lk
78.47.-p
Opis:
Systematic studies of neutral heavy-hole excitonic line energy changes in a strong excitation regime were carried out by means of a pump-probe method for quantum wells containing a 2D gas of free holes. Energy shift of $X_{e1hh1}$ line was analyzed for different excitation energies at fixed delay between pump and probe pulses, also under external magnetic field. It was observed that this shift depends not only on the density of created excitons but also directly on the pump energy. In co-polarization configuration for excitation energy below an absorption resonance the energetic blue shift rises linearly with the elevated exciton density (localized excitons are created). For energies slightly above the resonance, the blue shift diminishes dramatically in spite of high exciton density present (delocalized excitons are created). Model absorption calculations are in qualitative agreement with the experimental data.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 849-851
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-Ohmic Conductivity of High Resistivity CdTe
Autorzy:
Łusakowski, J.
Szczytkowski, J.
Szadkowski, K.
Kamińska, E.
Piotrowska, A.
Karczewski, G.
Wojtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1933850.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.-r
Opis:
Conductivity measurements were carried out at room temperature on samples of nominally undoped Bridgman, bulk crystals and MBE-grown layers of CdTe. The samples were equipped with indium contacts which made it possible to determine the voltage distribution along the path of the current flow. The results show that for both types of CdTe almost all of the applied voltage drops in the vicinity of the positively biased contact. The resistance of the samples was shown not to depend on the distance between the pads. The results agree with predictions of model of current injection into semiconductors with deep traps.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 803-806
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:
Optical Characterization of MBE-Grown Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te Layers by Raman Spectroscopy
Autorzy:
Szuszkiewicz, W.
Dynowska, E.
Janik, E.
Karczewski, G.
Wojtowicz, T.
Kossut, J.
Jouanne, M.
Powiązania:
https://bibliotekanauki.pl/articles/1945228.pdf
Data publikacji:
1996-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.-e
75.50.Pp
78.30.-j
Opis:
In this paper we discuss a possibility of an optical characterization of thin semiconductor epilayers by Raman scattering measurements. As an example zinc blende Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te epilayers (0.66 ≤ x ≤ 1.0) have been grown by molecular beam epitaxy method and investigated by Raman scattering and X-ray diffraction. Information resulting from both methods is compared and discussed.
Źródło:
Acta Physica Polonica A; 1996, 89, 3; 335-340
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Scattering by Phonons and Magnons in MBE-Grown Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te Layers
Autorzy:
Szuszkiewicz, W.
Jouanne, M.
Dynowska, E.
Janik, E.
Karczewskl, G.
Wojtowicz, T.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1934042.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Ds
63.20.-e
78.30.Fs
Opis:
Collective excitations have been analyzed for Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te epilayers (0.66 ≤ x ≤ 1) by the Raman scattering studies performed at temperatures from 7 K to 295 K. Apart from the lattice optical modes magnetic excitations (magnons) were observed at sufficiently low temperatures.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 941-944
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:
Light-Induced Gratings in CdMnTeSe:In Crystals
Autorzy:
Koziarska-Glinka, B.
Ponder, M.
Wojtowicz, T.
Miotkowski, I.
Langer, J. M.
Suchocki, A.
Powiązania:
https://bibliotekanauki.pl/articles/1968302.pdf
Data publikacji:
1997-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.62.Dh
42.65.Hw
61.72.Ji
Opis:
We show that DX-like centers in Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{x}$:In crystal can be used in writing volume holographic gratings. The scattering efficiency is higher than 10% which proves the dispersive character of the light-induced gratings. Two different metastable centers with different lattice relaxation were found in the crystal. Measurements of the power dependence of the degenerate four-wave mixing scattering efficiency testify that both of these centers have negative U properties.
Źródło:
Acta Physica Polonica A; 1997, 92, 5; 883-886
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Interface-Induced Disorder on Classical and Quantum Conductivity of CdTe:IN Epitaxial Layers
Autorzy:
Łusakowski, J.
Karpierz, K.
Grynberg, M.
Karczewski, G.
Wojtowicz, T.
Contreras, S.
Callen, O.
Powiązania:
https://bibliotekanauki.pl/articles/1968369.pdf
Data publikacji:
1997-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.50.Jt
73.61.Ga
Opis:
An influence of disorder originated from the substratelayer interface on electrical properties of CdTe:In layers was investigated by means of the Hall effect and magnetoresistance measurements at low temperatures. An estimation of a scattering rate due to interface-induced disorder is given. Characteristic features of a magnetic field dependence of magnetoresistance are explained by an influence of quantum interference of scattered electron waves both in the hopping and the free electron conductivity regimes.
Źródło:
Acta Physica Polonica A; 1997, 92, 5; 911-914
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Excitonic Energy Shifts in CdMnTe/CdMgTe Quantum Wells under Resonant Excitation in Presence of 2D Carrier Gas
Autorzy:
Trajnerowicz, A.
Golnik, A.
Kossacki, P.
Bardyszewski, W.
Wiater, M.
Karczewski, G.
Wojtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1811999.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.De
71.35.Lk
78.47.-p
Opis:
Systematic studies of amplitude and energy changes of excitonic lines in a strong excitation regime were carried out by a pump-probe method. The series of samples containing quantum wells with well width from 80 Åto 140 Åwas investigated. One 80 Åsample was n-doped with iodine, the rest of the quantum wells were intentionally undoped but contained a 2D gas of free holes. Its density could be varied by changing an intensity of additional illumination. The resonant creation of high population of e1hh1 excitons causes the energetic blue shift of the same due to interactions between excitons. The blue shifts did not depend on the concentration of 2D gas of carriers whereas it did depend on the power of excitation beam. Model calculations of absorption show qualitative agreement with the experimental data.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1403-1409
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Many-Body Interaction Evidenced through Exciton-Trion-Electron Correlated Dynamics
Autorzy:
Portella-Oberli, M. T.
Berney, J. H.
Deveaud, B.
Ciulin, V.
Kutrowski, M.
Wojtowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/2038371.pdf
Data publikacji:
2004-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.Pq
78.47.+p
42.65.-k
78.67.De
Opis:
Interactions among excitons, trions, and electrons are studied in CdTe modulation-doped quantum wells. These many-body interactions are investigated through the nonlinear dynamical properties in the excitonic complexes using time and spectrally resolved pump and probe techniques. This study is performed as a function of temperature and densities of excitons, trions, and electrons. The results reveal that the nonlinearities induced by trions differ from those induced by excitons and moreover they are mutually correlated. The correlated behavior of excitons and trions manifests itself by crossed trion-exciton effects. We propose that the main source of these correlations is due to the presence of electrons in the quantum well and that its physical origin is the Pauli exclusion-principle. We find that, at 5 K, trions are formed from excitons within 10 ps; at 20 K a thermal equilibrium is reached within 5 ps.
Źródło:
Acta Physica Polonica A; 2004, 106, 3; 423-434
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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