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Wyszukujesz frazę "Godlewski, J." wg kryterium: Autor


Tytuł:
Space Charge Limited Currents in Anthracene Crystals under Modulated Illumination
Autorzy:
Uzarczyk, A.
Godlewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933388.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
Opis:
Space charge limited currents have been examined in anthracene crystals illuminated with a chopped beam of monochromatic light (λ = 420 nm). The beam was uniformly absorbed in the anthracene crystal. The primary objective of our research was to determine mechanisms responsible for the release and trapping of charge carriers in the case of space charge limited currents as a function of time. The experimental results concern the dependences of photocurrents on the frequency of light chopping, light intensity, voltage and current decay after illumination. Photocurrent decay as a function of time was exponential for short time periods (i.e. for milliseconds), while for longer periods it was described by the power function t$\text{}^{-1/l}$, where parameter 1 is the characteristic parameter of the exponential distribution of traps.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 849-854
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electric Current Flow through Tetracene Layer-Anthracene Crystal Junction
Autorzy:
Signerski, R.
Godlewski, J.
Sodolski, H.
Powiązania:
https://bibliotekanauki.pl/articles/1933385.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
Opis:
Theoretical and experimental analysis was carried out on electric currents limited by the potential barrier governing the flow of holes from the tetracene layer to the anthracene crystal. Theoretical spatial distributions of charge carriers near the barrier were determined, as well as current-field dependences for the currents flowing through the investigated junction in the presence and in the absence of illumination. A current-field characteristic of the junction conditioned current is described by dependence of the j ∝ E$\text{}_{0}^{3}$ type in the presence of illumination and by the j ∝ E$\text{}_{0}^{2l+1}$ type in the lack of illumination, where l is the characteristic parameter of the trap distribution. Experimental research of the hole currents flowing through the polycrystalline tetracene layer-anthracene monocrystal junction confirmed the theoretical predictions about the current-field characteristics. A remarkably unequivocal confirmation was obtained for the current-field dependences in the presence of illumination.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 843-847
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Analysis of Photoenhanced Electric Currents in Molecular Materials
Autorzy:
Jarosz, G.
Signerski, R.
Godlewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933390.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
Opis:
This paper presents numerical calculations of photoenhanced current-applied voltage and photoenhanced current-light intensity characteristics with regard to the exciton diffusion length, lifetime of excitons and rate of exciton surface quenching. Dependencies of this type cannot be obtained analytically. It is shown that the increase in diffusion length causes the decrease in current in the case of strong surface quenching of excitons. Simultaneously, it is shown that the quality of crystals influences the photoenhanced current. A better quality of crystals causes the increase in the current in the case of weak surface quenching of excitons.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 855-860
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge Carrier Generation Caused by X-Rays in Organometallic Materials
Autorzy:
Godlewski, J.
Signerski, R.
Jarosz, G.
Stizza, S.
Berrettoni, M.
Powiązania:
https://bibliotekanauki.pl/articles/2011031.pdf
Data publikacji:
1999-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
Opis:
Organometallic compounds play an exceptional role among organic compounds. Due to their structure a number of these compounds demonstrate interesting properties in various phenomena. Organometallic compounds show special properties in the case of X-ray absorption owing to considerable differences between the absorption coefficients of metals and light elements. The analysis of processes of charge carrier generation as a result of X-ray absorption in chosen organometallic compounds is the subject of this paper. Spectral dependences of charge carrier photogeneration efficiency around the Cu K-edge in copper phthalocyanine and copper acetylacetoniane have been specially considered. It has been observed that the photocurrent spectrum in these materials follows the absorption spectrum but mutual relation is not directly proportional. Experimental results connected with current-voltage and current-intensity characteristics have been analysed, as well. The obtained relationships have been compared with adequate results connected with charge carrier photogeneration in visible area and UV in organic materials. It has been observed that the X-ray photogeneration of charge carriers in the examined range of energy differs from the mechanisms of charge carrier generation in visible area and UV. The basic differences arise from the participation of secondary electrons, which are generated due to Auger electrons, Compton effect, and metal fluorescence. The process of charge carrier generation as a result of X-rays absorption is characterized by strong recombination of charge carriers in channels in which charge carriers are generated by high energetic secondary electrons.
Źródło:
Acta Physica Polonica A; 1999, 96, 2; 295-301
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Synthesis Pressure on Properties of Eu-Doped ZnO Nanopowders Prepared by Microwave Hydrothermal Method
Autorzy:
Rosowska, J.
Kaszewski, J.
Witkowski, B.
Wachnicki, Ł.
Godlewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1185714.pdf
Data publikacji:
2016-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Hx
81.07.Wx
81.20.Ka
78.60.Hk
Opis:
In the current research, europium doped ZnO nanopowders prepared by a microwave hydrothermal method are investigated. The effects of synthesis pressure on the morphologies, crystal structures, and optical properties of Eu-doped ZnO were analyzed by scanning electron microscopy, X-ray diffraction, cathodo- and photoluminescence. From our investigations it can be concluded that the synthesis pressure strongly influences the surface morphology. With the increase of the synthesis pressure from 2 MPa to 10 MPa significant changes can be observed. An increase of the mean crystallites sizes and change of the intensity ratio between the near band edge and defect related deep level emission band of ZnO were observed.
Źródło:
Acta Physica Polonica A; 2016, 130, 5; 1205-1208
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photo-ESR Studies of Ni doped ZnS and ZnSe
Autorzy:
Surma, M.
Zakrzewski, A. J.
Godlewski, M.
Surkova, T. P.
Powiązania:
https://bibliotekanauki.pl/articles/1932084.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
76.30.He
78.55.Et
Opis:
The results of electron spin resonance experiments are presented for nickel doped ZnS and ZnSe. Energy level position of Ni$\text{}^{1+}$ state in band gap of ZnS and ZnSe is determined. The nonradiative recombination processes of donor-acceptor pairs in Ni doped samples are discussed.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 221-224
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:
Effect of Annealing on the Crystal Structure and Microstructure of Pr Doped $ZrO_{2}-Y_{2}O_{3}$ Nanocrystals
Autorzy:
Werner-Malento, E.
Paszkowicz, W.
Fidelus, J.
Godlewski, M.
Yatsunenko, S.
Powiązania:
https://bibliotekanauki.pl/articles/1550117.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.-w
61.66.Fn
81.40.-z
Opis:
Rare-earth doped nanocrystalline yttria-stabilized zirconia (YSZ, $ZrO_{2}-Y_{2}O_{3}$) is, recently, a subject of studies because of its luminescent properties. The luminescence may be strongly influenced by the crystal structure and microstructure of the material. In this work, the X-ray diffraction study for Pr doped YSZ nanocrystals is presented. The phase composition dependence on the $Y_{2}O_{3}$ content and on heat treatment conditions is quantitatively determined using the Rietveld method and the similarities and differences between the present data for doped samples and earlier reported data for undoped material are discussed. A formation of high symmetry phases (cubic and tetragonal) is observed for high yttria content in agreement with general tendencies observed in literature for undoped samples.
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 91-97
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Growth Conditions on Optical Properties of ZnCdSe/ZnSe Quantum Wells Grown by Molecular Beam Epitaxy
Autorzy:
Godlewski, M.
Bergman, J. P.
Monemar, B.
Kurtz, E.
Hommel, D.
Powiązania:
https://bibliotekanauki.pl/articles/1950749.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.60.-p
71.35.+z
76.70.Hb
Opis:
The results of investigations of photoluminescence, time-resolved photoluminescence, photoluminescence kinetics and their temperature dependencies are discussed for two types of ZnCdSe/ZnSe multi quantum well structures - for pseudomorphic and for strain relaxed structure. Densities of 2D localized states and averaged localization energies, as seen by excitons, are determined from the photoluminescence kinetics measurements. We show distinct differences between exciton properties in two multi quantum well structures studied.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 785-788
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Properties of GaN Epilayers grown by Gas Source Molecular Beam Epitaxy on AlN Buffer Layer on (111) Si
Autorzy:
Godlewski, M.
Bergman, J. P.
Monemar, B.
Rossner, U.
Barski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1950766.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
71.35.+z
78.47.+p
Opis:
Optical properties of GaN/AlN/Si (111) epilayers grown by MBE are studied. The observed decay transients of excitonic emissions and their temperature dependence is explained by an efficient transfer link between bound and free excitons.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 789-792
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Excitation and Recombination Processes in InAs$\text{}_{x}$P$\text{}_{1-x}$:Yb (x=0.04, 0.07 and 0.11)
Autorzy:
Godlewski, M.
Kozanecki, A.
Karpińska, K.
Bergman, J. P.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1932083.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
78.55.Cr
71.35.+z
Opis:
Excitation and recombination mechanisms of Yb$\text{}^{3+}$ 4f-4f intra-shell emission in InP and InAsP (4, 7 and 11% of As) are analyzed.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 217-220
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonradiative Recombination Processes in (CdTe,CdCrTe)/CdMgTe Quantum Well Structures
Autorzy:
Godlewski, M.
Ivanov, V.
Zakrzewski, A. J.
Wojtowicz, T.
Karczewski, G.
Kossut, J.
Bergman, J. P.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1968108.pdf
Data publikacji:
1997-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.60.-p
76.70.Hb
Opis:
Photoluminescence transitions in (CdTe,CdCrTe)/CdMgTe structure grown by molecular beam epitaxy are studied. Photoluminescence investigations show a very strong reduction of the photoluminescence intensity from chromium doped quantum wells. We explain this fact by a very efficient nonradiative recombination in the chromium-doped quantum wells. The present results indicate that the Auger-type energy transfer from excitons to chromium ions is responsible for the photoluminescence deactivation. The efficiency of this process is evaluated.
Źródło:
Acta Physica Polonica A; 1997, 92, 4; 781-784
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Optical Properties of CdTe/CdMnTe Quantum Wells Grown by Molecular Beam and Atomic Layer Epitaxy
Autorzy:
Godlewski, M.
Kopalko, K.
Wojtowicz, T.
Karczewski, G.
Kossut, J.
Bergman, J. P.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1952470.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.+z
78.47.+p
78.55.Et
Opis:
Optical properties of a series of CdTe/CdMnTe multi quantum well structures grown with MBE and ALE (CdTe quantum wells only) methods are compared. Based on the results of the photoluminescence experiments we conclude that the ALE growth leads to a different lateral scale of quantum well width fluctuations, which results in different exciton properties in two multi quantum well systems studied. In the wells grown with ALE method excitons are less localized. They can migrate in a quantum well plane between quantum well regions varying in thickness by 1 monolayer.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 1012-1016
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exciton Properties in CdTe/CdMnTe Quantum Well Structures with Strong Localization Effects
Autorzy:
Godlewski, M.
Narkowicz, R.
Wojtowicz, T.
Karczewski, G.
Kossut, J.
Bergman, J. P.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1969075.pdf
Data publikacji:
1998-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.-y
71.55.Jv
73.20.Mf
Opis:
Strong localization effects present in quantum well structures of CdTe/ CdMnTe noticeably affect exciton dynamics and strength and character of exciton-phonon interaction. We show that the temperature dependences of the PL linewidth, PL peak wavelength and PL decay time strongly deviate from those expected for Wannier-excitons in structures with atomically smooth interfaces.
Źródło:
Acta Physica Polonica A; 1998, 94, 2; 317-320
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Properties of ZnCoO Films and Nanopowders
Autorzy:
Wolska, E.
Łukasiewicz, M.
Fidelus, J.
Łojkowski, W.
Guziewicz, E.
Godlewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1791349.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Ln
78.55.Et
81.07.Wx
61.72.uf
78.66.Hf
Opis:
ZnCoO is one of the most studied and promising semiconductor materials for spintronics applications. In this work we discuss optical and electrical properties of ZnCoO films and nanoparticles grown at low temperature by either atomic layer deposition or by a microwave driven hydrothermal method. We report that doping with cobalt quenches a visible photoluminescence of ZnO. We could observe a visible photoluminescence of ZnO only for samples with very low Co fractions (up to 1%). Mechanisms of photoluminescence quenching in ZnCoO are discussed. We also found that ZnO films remained n-type conductive after doping with Co, indicating that a high electron concentration and cobalt 2+ charge state can coexist.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 918-920
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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