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Tytuł:
Electron Transport in Submicron Wires of Semiconductors
Autorzy:
Wróbel, J.
Powiązania:
https://bibliotekanauki.pl/articles/1947015.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Rn
73.20.Fz
73.61.Ga
75.50.Pp
Opis:
We review the methods of fabrication and transport properties of submicron II-VI, IV-VI and III-V semiconductor wires. Devices were prepared by electron-beam lithography and used for detailed magnetotransport studies, carried out at low (down to 30 mK) temperatures. We discuss a number of novel features obtained in ballistic, diffusive and localized transport regimes. In particular, we describe the universal conductance fluctuations for semimagnetic materials (CdMnTe) and discuss the edge channel transport for PbTe, PbSe and GaAs/GaAlAs systems.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 691-701
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical and Optoelectronic Properties of ZnS Nanostructured Thin Film
Autorzy:
Borah, J.
Sarma, K.
Powiązania:
https://bibliotekanauki.pl/articles/1812035.pdf
Data publikacji:
2008-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ga
73.61.Tm
74.25.Gz
Opis:
ZnS nanocrystalline thin films were grown into the polyvinyl alcohol matrix and were synthesized by chemical route. Films were prepared on glass substrate by varying the deposition parameters and pH of the solution. Nanocrystalline thin film prepared under optimum growth conditions shows band gap value 3.88 eV as observed from optical absorption data. The band gap is found to be higher (3.88 eV) indicating blue shift. The particle size, calculated from the shift of direct band gap, due to quantum confinement effect is 5.8 nm. Photoluminescence spectrum shows the blue luminescence peaks (centered at 425 nm), which can be attributed to the recombination of the defect states. ZnS nanocrystalline thin films are also found to be photosensitive in nature. However, the photosensitivity decreases due to ageing and exposure to oxygen. In case of nanostructured film, the I-V characteristics are observed in dark and under illumination showing photosensitive nature of these films, too. The dark current, however, is found to be greater when observed in vacuum compared to air. Both dark current and photocurrent are found to be ohmic in nature up to a certain applied bias. The observed data shows that nanostructured films are found to be suitable for device application. The surface morphology of the film is also characterized by scanning electron microscope.
Źródło:
Acta Physica Polonica A; 2008, 114, 4; 713-719
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exciton Binding Energy in Extremely Shallow Quantum Wells
Autorzy:
Kossut, J.
Furdyna, J. K.
Powiązania:
https://bibliotekanauki.pl/articles/1877012.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
71.36.+c
73.61.Ga
Opis:
The usual approach to the problem of excitons in semiconductor quantum wells is to assume that both the electron or the hole are primarily localized in the potential well regions defined by the band offsets, i.e., that the quantum wells are deep. We re-examine the problem of the exciton in the presence of a very shallow square well potential due to the (small) conduction and valence band offsets in a semiconducting heterostructure. We show that the combined effects of the shallow well and the Coulomb interaction between the electron and the hole are equivalent to an effective potential acting on the center-of-mass of a three-dimensional exciton. We calculate the shape of such a potential and show it to be satisfactorily approximated by the potential of a parabolic well.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 528-532
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Magnetic Impurities upon Universal conductance Fluctuations
Autorzy:
Dietl, T.
Powiązania:
https://bibliotekanauki.pl/articles/1953174.pdf
Data publikacji:
1997-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
72.15.Rn
73.61.Ga
73.20.Fz
Opis:
Mesoscopic phenomena in quantum structures which incorporate magnetic impurities with localized spins may exhibit a number of novel features driven by spin-disorder scattering, exchange spin-splitting of electron bands, and the formation of bound magnetic polarons. After brief information on these effects, their influence on universal conductance fluctuations as well as on low frequency noise and quantum localization is presented. Millikelvin investigations of diffusive charge transport, which have been carried out for submicron wires of n$\text{}^{+}$-Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te epilayers, are reviewed in some details. These studies have provided information on the significance of spin-disorder scattering in semiconductors and put into the evidence a new driving mechanism of the magnetoconductance fluctuations - the redistribution of the electrons between energy levels of the system, induced by the giant s-d exchange spin-splitting. Important implications of these findings for previous interpretations of spin effects in semiconductor and metal nanostructures are discussed.
Źródło:
Acta Physica Polonica A; 1997, 91, 1; 161-171
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport in Quantum Structures of Diluted Magnetic Semiconductors
Autorzy:
Jaroszyński, J.
Powiązania:
https://bibliotekanauki.pl/articles/2011139.pdf
Data publikacji:
1999-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.50.Td
72.15.Rn
73.61.Ga
75.50.Lk
Opis:
This paper reviews recent millikelvin studies of magnetoconductance and noise in nanostructures of a diluted magnetic semiconductor n-Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te. These studies were particularly rewarding for probing the influence of magnetic ions upon mesoscopic phenomena. The accumulated results demonstrated the existence of a new driving mechanism of the universal conductance fluctuations in magnetic systems. Several signatures of spin-glass freezing were observed, such as the appearance of 1/f conductance noise, aging, thermal, and magnetic irreversibilities as well as a strong increase in the amplitude of both conductance fluctuations and noise when temperature and the magnetic field were lowered below the freezing line. A statistical analysis of conductance noise made it possible to investigate the nature of excitations in spin-glass phase, and to discriminate between competing theoretical models.
Źródło:
Acta Physica Polonica A; 1999, 96, 5; 641-650
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interpretation of Switching Properties of $InGaSe_2$ Single Crystal
Autorzy:
Al Orainy, R.
Powiązania:
https://bibliotekanauki.pl/articles/1489875.pdf
Data publikacji:
2012-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.-e
78.66.-w
73.61.Ga
74.25.Gz
Opis:
The goal of this paper is to present experimental results of the switching effect and analyze qualitatively the influence of various factors, such as temperature, light illumination and sample thickness on switching behavior of the high quality ternary chalcogenide semiconductor $InGaSe_2$. Current-controlled negative resistance of $InGaSe_2$ single crystals has been observed for the first time. It has been found that indium gallium diselenide single crystals exhibit bistable or memory switching. The switching process takes place with both polarities on the crystal and has symmetric shapes. Current-voltage characteristics of $Ag-InGaSe_2-Ag$ structures exhibit two distinct regions, high resistance OFF state and low-resistance ON state having negative differential resistance. $InGaSe_2$ is a ternary semiconductor exhibiting S-type I-V characteristics. The specimen under test showed threshold switching with critical field of the switching being $10^3$ V/cm at room temperature.
Źródło:
Acta Physica Polonica A; 2012, 121, 3; 666-672
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrostatic Pressure Study of MBE CdMnTe Doped with Bromine
Autorzy:
Szczytko, J.
Wasik, D.
Przybytek, J.
Baj, M.
Waag, A.
Powiązania:
https://bibliotekanauki.pl/articles/1934026.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
73.61.Ga
Opis:
We present Hall effect and resistivity measurements as a function of pressure performed on MBE-grown Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te (with x = 0.14) layer (1 μm) doped with bromine. The experimental data were analysed using positive and negative U model of the Br centres. We found that both models could reproduce the experimental points, but in the case of positive U model - only under assumption that the sample was completely uncompensated.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 933-936
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical Analysis of Optical Losses in CdS/CdTe Solar Cells
Autorzy:
Roshko, V.
Kosyachenko, L.
Grushko, E.
Powiązania:
https://bibliotekanauki.pl/articles/1492967.pdf
Data publikacji:
2011-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.60.Jt
85.60.Dw
73.61.Ga
Opis:
Based on the known refractive index and extinction coefficient, calculations of optical losses in glass/transparent conducting oxide/CdS/CdTe solar cells have been carried out taking into account reflections at the interfaces and absorption in the transparent conducting oxide (indium tin oxide or $SnO_2$:F) and CdS layers. It has been shown that the losses caused by reflections at the interfaces result in lowering the short-circuit current by ≈ 9% whereas absorption in the transparent conducting oxide and CdS layers with the typical thicknesses lead to losses of 15-16% for glass/$SnO_2$/CdS/CdTe, and 22-24% for glass/indium tin oxide/CdS/CdTe solar cells.
Źródło:
Acta Physica Polonica A; 2011, 120, 5; 954-956
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Injection of Optically Generated Spins through Magnetic Nonmagnetic Heterointerface: Ruling out Possible Detection Artifacts
Autorzy:
Ghali, M.
Kossut, J.
Janik, E.
Powiązania:
https://bibliotekanauki.pl/articles/2038227.pdf
Data publikacji:
2004-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.-n
73.61.Ga
Opis:
We report on injection of optically created spin-polarized carriers into CdTe-based materials. The injected spins are initially aligned in a diluted magnetic semiconductor CdMnTe layer located on the top of CdMgTe layer in CdMnTe/CdMgTe spintronic generic model structures. A critical discussion of possible artifacts that may complicate the spin detection and its quantitative analysis is given. Although the spin injection efficiency, 80%, has been found by us to be basically independent of the thickness of the spin detecting layer, there is an essential difference between thin and wide detectors related to the strain-induced lifting of the valence band degeneracy in the former, when assessing the efficiency of the spin injection. Most importantly, we observe an effect of switching the spin injection process on and off by an external magnetic field variation within a relatively narrow field range. This effect can be achieved by a careful design of the interface between the diluted magnetic semiconductor and the non-magnetic semiconductor.
Źródło:
Acta Physica Polonica A; 2004, 106, 2; 207-214
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence Properties of Manganese Doped CdS Nanoparticles under Various Synthesis Conditions
Autorzy:
Salimian, S.
Farjami Shayesteh, S.
Powiązania:
https://bibliotekanauki.pl/articles/1535741.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ga
74.25.Gz
78.55.Et
81.16.Be
Opis:
An aqueous solution method has been developed for synthesizing size-controlled $Mn^{2+}$ doped CdS nanocrystals with a relatively narrow size distribution. The nanocrystal samples were characterized by UV-Vis absorption spectra and photoluminescence spectra. We prepared narrow size distribution particles under different synthesis conditions. The effect of manganese concentration on the photoluminescence properties was investigated. Luminescence intensity in different excitation wavelength correlates with different size of CdS:Mn nanocrystals on luminescence spectra. We found that by narrowing the size distribution and doping concentration, CdS samples can be prepared with high luminescence intensity.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 633-636
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Limitations on Thickness of Absorber Layer in CdS/CdTe Solar Cells
Autorzy:
Mykytyuk, T.
Roshko, V.
Kosyachenko, L.
Grushko, E.
Powiązania:
https://bibliotekanauki.pl/articles/1409388.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.60.Jt
85.60.Dw
73.61.Ga
Opis:
Calculations of the integrated absorptive capacity of CdTe layer taking into account the spectrum of the AM1.5 solar radiation and the absorption coefficient of CdTe are carried out. The recombination losses at the front and rear surfaces of the CdTe layer and in the space-charge region are also calculated based on the continuity equation. The restrictions on the thickness of CdTe in CdS/CdTe heterojunction have been ascertained taking into account all types of losses. It is shown that in CdTe, the almost complete absorption of photons (99.9%) in the hν > $E_{g}$ range is observed at a layer thickness of more than 20-30 μm, and the absorptive capacity of photons in a CdTe layer of thickness 1 μm is about 93%. The obtained results indicate that when the CdTe absorber layer is very thin, it is impossible to avoid a noticeable decrease of the short circuit current density $J_{sc}$ as compared with a typical thickness of the absorber layer. The loss in $J_{sc}$ is 19-20% when the thickness is 0.5 μm compared to 5% for a thickness of 2-3 μm.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1073-1076
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:
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:
Hole Traps in ZnTe with CdTe Quantum Dots
Autorzy:
Zielony, E.
Płaczek-Popko, E.
Gumienny, Z.
Trzmiel, J.
Karczewski, G.
Guziewicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/1791335.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ga
73.21.La
73.20.Hb
Opis:
In this study the capacitance-voltage (C-V) and deep level transient spectroscopy measurements have been performed on ZnTe (p-type)-Ti/Al Schottky diodes containing a layer of CdTe self-assembled quantum dots and on the reference diodes without dots for comparison. Both kinds of investigated samples were grown by molecular beam epitaxy technique. The dots were formed during the Stransky-Krastanov growth mode. Comparison of the C-V and deep level transient spectroscopy results obtained for both samples allows us to conclude that the 0.26 eV trap observed exclusively for the QD sample can be assigned to some defects in a wetting layer or CdTe/ZnTe interface.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 885-887
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anharmonic Optical Phonon Effects in ZnO Nanocrystals
Autorzy:
Khusnutdinov, S. V.
Dynowska, E.
Zaleszczyk, W.
Makhniy, V. P.
Wysmołek, A.
Korona, K. P.
Powiązania:
https://bibliotekanauki.pl/articles/2048106.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ga
74.25.nd
63.20.kg
Opis:
Zinc oxide (ZnO) is a very promising material for optoelectrical devices operating at the short-wavelength end of the visible spectral range and at the near UV. The Raman scattering studies of ZnO heterolayers formed by isothermal annealing show sharp phonon lines. In addition to the A$\text{}_{1}$(TO), E$\text{}_{1}$(TO), E$\text{}_{2}^{H}$, and E$\text{}_{1}$(LO) one-phonon lines, we observed two-phonon lines identified as: E$\text{}_{2}^{H}$ - E$\text{}_{2}^{L}$, E$\text{}_{2}^{H}$ + E$\text{}_{2}^{L}$, and 2LO at 332, 541, and 1160 cm$\text{}^{-1}$, respectively (at room temperature). The identification of the E$\text{}_{2}^{H}$ - E$\text{}_{2}^{L}$ peak was confirmed by its thermal dependence. Temperature dependent measurements in the range 6-300 K show that the phonon frequencies decrease with temperature. The E$\text{}_{2}^{H}$ peak is at energy 54.44 meV (439.1 cm$\text{}^{-1}$), at 4 K and due to phonon-phonon anharmonic interaction, its energy decreases to 54.33 meV (438.2 cm$\text{}^{-1}$) at room temperature. The Grüneisen parameter found for this oscillation mode was γ$\text{}_{E}$ 2H = 1.1 at about 300 K. The intensity of the E$\text{}_{2}^{H}$ - E$\text{}_{2}^{L}$ peak increases strongly with temperature and this dependence can be described by the Bose-Einstein statistics with activation energy of 13.8 meV (nearly equal to the energy of the E$\text{}_{2}^{L}$ phonon).
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 678-680
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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