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Wyszukujesz frazę "72.20.-I" wg kryterium: Temat


Tytuł:
Indications for Diamagnetic Shift in the Ground State of Boron in Silicon
Autorzy:
Stöhr, M.
Chroboczek, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/1891427.pdf
Data publikacji:
1991-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Ht
71.70.-d
72.20.-i
Opis:
Indications for the observation of the diamagnetic shrinkage of the boron acceptor wave function (WF) in Si are reported. Uniaxial stress (X) was used to split the ground state (GS) of the boron acceptor into two energy levels with spatially complementary WF. The magnetic field selectively induces a shrinking of one of the two WF, depending on whether it is applied parallel or perpendicular to the X axis. As a result, the hopping transitions between lower and higher energy levels are redistributed, leading to significant changes in the activation energy ε$\text{}_{3}$. This effect was borne out by experiment.
Źródło:
Acta Physica Polonica A; 1991, 80, 3; 465-468
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoconductivity in GaAlAs:Si Proves Negative U of DX Centers
Autorzy:
Wilamowski, Z.
Jantsch, W.
Ostermayer, G.
Powiązania:
https://bibliotekanauki.pl/articles/1888154.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Jv
71.55.-i
Opis:
The analysis of the temperature dependence of the photoconductivity, amplitude in doped GaAlAs, provides a simple and convincing proof of the negative sign of the Hubbard correlation energy U, strictly speaking of the two-electron nature of the thermal emission process from DX centers. The proof is based on a comparison of the emission activation energy measured per emission event (DLTS) with that measured per electron.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 283-286
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
DX Puzzle: Where Are We Now?
Autorzy:
Wilamowski, Z.
Suski, T.
Jantsch, W.
Powiązania:
https://bibliotekanauki.pl/articles/1920958.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Jv
71.55.-i
Opis:
A brief review of the experimental data on the metastable DX-centers in AlGaAs is presented. The experimental proofs of the two-electron nature and of the intermediate, one-electron state of the DX-centers are discussed. We collect the available experimental data on the ground state, electron-emission and capture energies and we discuss the nature of the lattice barrier. The effect of splitting of these energies in AlGaAs alloys and the consequences of the splitting on the capture and emission kinetics are analyzed. The different character of the barrier and of the alloy splitting for donors of the IV and VI group is underlined. The necessity to consider the interdonor Coulomb interaction when discussing the experimental data is also pointed out.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 561-571
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Concentration Anomalies of Properties in Pb$\text{}_{1-x}$Ge$\text{}_{x}$Te Solid Solutions
Autorzy:
Rogacheva, E. I
Sinelnik, N. A
Nashchekina, O. N.
Powiązania:
https://bibliotekanauki.pl/articles/1929740.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.Ji
72.20.-i
71.45.-d
Opis:
The investigation of electrical conductivity, coefficient of thermal electromotive force, Hall coefficient, microhardness and mobility in Pb$\text{}_{1-x}$Ge$\text{}_{x}$Te (x = 0 ÷ 0.1) alloys in the temperature range of 77-300 K was carried out. Anomalies were detected in isotherms of properties in the vicinity of x = 0.008. The anomalies were treated as a manifestation of concentration phase transitions occurring in solid solutions of any kind and associated with existence of critical concentration (percolation threshold) at which the uninterrupted chain of interactions between impurity atoms is formed.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 729-732
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coulomb versus Madelung Gap: Ordering in a System of Point Charges
Autorzy:
Sobkowicz, P.
Wilamowski, Z.
Kossut, J.
Powiązania:
https://bibliotekanauki.pl/articles/1929618.pdf
Data publikacji:
1993-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.-i
72.20.Fr
Opis:
Spatial correlations of impurity charges in a mixed valence regime are studied with the use of Monte Carlo simulations. The influence of various kinds of disorder on the one-particle density of states is determined. A continuous transitions from a "soft" Coulomb gap (density of states vanishing only at the chemical potential) to a "hard" gap (with a finite range of energies with vanishing density of states) is found, driven by decreasing amount of built-in disorder in the system. The "hard" Coulomb gap resembles the Madelung gap, found in crystalline arrangements of charges. The similarity reflects the fact that both the Coulomb and Madelung gaps are manifestations of the same phenomenon, resulting from ordering of the positions of point charges, the only difference being the range of correlations.
Źródło:
Acta Physica Polonica A; 1993, 84, 3; 515-518
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport Properties in 2,6-Diamino Anthraquinone
Autorzy:
Khalil, S. M.
Darwish, S.
Powiązania:
https://bibliotekanauki.pl/articles/1931351.pdf
Data publikacji:
1994-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.-i
Opis:
Current density-voltage characteristics were obtained from 2,6-diamino anthraquinone samples using ohmic aluminium electrodes. Results showed that at low voltage the conduction process was ohmic, while at high voltage space-charge-limited conduction controlled by a single dominant trap level was presented. Thickness dependence measurements proved that the trapping sites were located at a discrete energy level. The transition voltage, V, between ohmic and space-charge-limited conduction was approximately proportional to the square of the sample thickness and was found to be temperature independent. The temperature dependence of ohmic and space-charge-limited current densities have been investigated. The results were interpreted in terms of extrinsic nature of ohmic conduction. Traps with density ≈ 2 × 10$\text{}^{24}$ m$\text{}^{-3}$ located at 0.50 ± 0.03 eV below the conduction band edge have been observed.
Źródło:
Acta Physica Polonica A; 1994, 85, 6; 953-958
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Oxygen Impurities on Electrical Properties of Fullerene C$\text{}_{60}$
Autorzy:
Rabenau, T.
Roth, S.
Kremer, R. K.
Powiązania:
https://bibliotekanauki.pl/articles/1933397.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Jv
72.80.Le
72.20.-i
Opis:
We present high temperature dc, ac and contactless microwave conductivity results on solid-state C$\text{}_{60}$ (films and crystals) from room temperature up to 850 K. Heating pristine samples, which were exposed to the ambient atmosphere, under dynamic vacuum at first leads to a reduction of the electrical resistance and finally, above ≈700 K, to an increase in the resistance. The decrease is ascribed to oxygen desorption and the increase to the chemical reactivity of residual chemisorbed oxygen with the C$\text{}_{60}$ host molecules, respectively. Samples, annealed above 800 K, display a reversible temperature dependence of the resistance. The high temperature regime of their resistance exhibits an activated behaviour with an universal activation energy of 2E$\text{}_{a}$ = 1.85 ± 0.04 eV for crystals and films, which is identical to the HOMO-LUMO splitting of the C$\text{}_{60}$-molecules.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 881-884
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metastability of Localized Neutral Donor State In GaAs
Autorzy:
Skierbiszewski, C.
Jantsch, W.
Lübke, K.
Wilamowski, Z.
Suski, T.
Powiązania:
https://bibliotekanauki.pl/articles/1933994.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Fr
71.55.-i
Opis:
Investigations of the photoconductivity of GaAs:Ge under hydrostatic pressure show, in addition to the well known persistent photoconductivity due to the DX state, another giant photoconductivity caused by a neutral localised "A₁" state of the donor. We find that the top of the barrier for the electron recapture to the Α₁ state is pinned to the conduction band edge and the capture cross-section σ(T → ∞) is surprisingly small.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 905-908
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Novel Organic Semiconductor BTQBT with High Conductivity and High Mobility
Autorzy:
Inokuchi, H.
Imaeda, K.
Powiązania:
https://bibliotekanauki.pl/articles/1943958.pdf
Data publikacji:
1995-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.60.-i
72.20.-i
Opis:
We have found a novel organic semiconductor, BTQBT, with a high electrical conductivity of about 10$\text{}^{-3}$ S cm$\text{}^{-1}$ and a high Hall mobility of about 3 cm$\text{}^{2}$ V$\text{}^{-1}$s$\text{}^{-1}$ at room temperature. We have also succeeded in measuring the temperature dependence of the Hall mobility. It varies with temperature as Τ$\text{}^{-1.6}$, which agrees with the theoretical Τ$\text{}^{-1.5}$ dependence for the mobility determined by lattice scattering. The characteristic transport property of BTQBT results from strong intermolecular interactions in the crystal, which is convinced by the energy dispersion with a bandwidth of about 0.5 eV from the theoretical and experimental band structures.
Źródło:
Acta Physica Polonica A; 1995, 88, 6; 1161-1170
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polaron Problem in Quantum Wells
Autorzy:
Bardyszewski, W.
Prywata, M.
Powiązania:
https://bibliotekanauki.pl/articles/1934053.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ey
71.38.+i
73.20.Dx
Opis:
The effect of polar interaction between an electron in a quantum well and bulk longitudinal optical phonons is analysed. Electron spectral density function is calculated in the lowest order cumulant approximation. The position and linewidth of the quasiparticle peak are obtained as a function of quantum well width and temperature.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 969-973
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
State of the Art Molecular Beam Epitaxy of III-V Compounds
Autorzy:
Foxon, C. T.
Powiązania:
https://bibliotekanauki.pl/articles/1933668.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
85.60.-q
61.50.Cj
68.55.Bd
72.20.-i
Opis:
This paper discusses molecular beam epitaxy with particular emphasis on the production of state of the art electronic and optoelectronic low dimensional structures and devices. The molecular beam epitaxy process is outlined briefly and the practical problems associated with producing "state of the art" (Al,Ga)As/GaAs structures are considered. Examples include high mobility electron and hole gases, low threshold current lasers and the multi-quantum well solar cells.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 559-566
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrical Properties of Lead Phthalocyanine Films
Autorzy:
Abd El-Rehim, N.
El-Samahy, A.
Powiązania:
https://bibliotekanauki.pl/articles/1946191.pdf
Data publikacji:
1996-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.-i
Opis:
Current density-voltage characteristics have been obtained from thin films of lead phthalocyanine particles dispersed in a polymer binder when sandwiched between ohmic gold and blocking aluminium electrodes. At low voltages, the current in the forward direction shows Schottky diode behaviour. The diode parameters are evaluated using the model of Cheung and Cheung. Barrier heights and widths are determined as a function of applied voltage. A number of parameters is evaluated on the basis of the theory of space-charge-limited conduction, and the following values are obtained: p$\text{}_{0}$ = 8.5 × 10$\text{}^{18}$ m$\text{}^{-3}$, concentration of the traps per unit energy range at the valence band P$\text{}_{0}$ ≈ 2.5 × 10$\text{}^{44}$ J$\text{}^{-1}$m$\text{}^{-3}$, temperature parameter of trapping distribution T$\text{}_{c}$ ≈ 500 K and total trapping concentration, N$\text{}_{t}$ ≈ 1.7 × 10$\text{}^{24}$ m$\text{}^{-3}$.
Źródło:
Acta Physica Polonica A; 1996, 90, 3; 557-564
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Scattering of Excitons by Phonons in Quantum Wells
Autorzy:
Bardyszewski, W.
Prywata, M.
Powiązania:
https://bibliotekanauki.pl/articles/1947245.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
71.38.+i
72.80.Ey
Opis:
A method to describe the effects of the exciton-optical phonon interaction is presented using the cumulant expansion approximation. The functional-integral technique of coherent phonon states is used in order to justify the commonly used model Hamiltonian and generate the proper perturbation series. The influence of the mutual electron-hole screening on the polaronic effects in quantum wells is analyzed.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 715-718
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoionization of Ge¯-DX State in GaAs
Autorzy:
Piotrzkowski, R.
Dmowski, L. H.
Powiązania:
https://bibliotekanauki.pl/articles/1968412.pdf
Data publikacji:
1997-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Mt
71.55.-i
72.40.+w
Opis:
We have determined the efficiency of photoionization of Ge¯-DX state in GaAs as a function of photon energy. The optical ionization energy derived from the fitting is about 1.0 eV. It proves a large difference between optical and thermal ionization energies and confirms that for Ge-impurity, the broken-bond model and large lattice relaxation are valid and not the breathing mode with small lattice relaxation, resulting from the calculations presented for Ge-impurity in T.M. Schmidt, A. Fazzio, M.J. Caldas, Mater. Sci. Forum 196/201, 273 (1995).
Źródło:
Acta Physica Polonica A; 1997, 92, 5; 950-952
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Energy Relaxation in Two-Dimensional Electron GaS in InGaAs/InP via Electron-Acoustic Phonon Interaction
Autorzy:
Kreshchuk, A. M.
Novikov, S. V.
Savel'ev, I. G.
Polyanskaya, T. A.
Pődör, B.
Reményi, G.
Kovács, Gy.
Powiązania:
https://bibliotekanauki.pl/articles/1991650.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.-i
Opis:
The energy relaxation in two-dimensional electron gas in In$\text{}_{0.53}$Ga$\text{}_{0.47}$As/InP has been studied in a wide range of electron temperatures (from 0.1 to 10 K). The energy loss rate of electrons is controlled by the interaction of electrons with the piezoelectric potential of acoustic phonons. The value of the piezoelectric constant for InGaAs lattice-matched to InP is deduced from theoretical fits of the experimental data: h$\text{}_{14}$=(1.1±0.1)×10$\text{}^{7}$ V/cm. Available data for the piezoelectric constant of In$\text{}_{x}$Ga$\text{}_{1-x}$As are discussed in the light of the results of this work.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 415-420
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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