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Wyszukujesz frazę "73.21.Hb" wg kryterium: Temat


Tytuł:
Acoustic Transport of Electrons in Parallel Quantum Wires
Autorzy:
Cunningham, J.
Pepper, M.
Talyanskii, V.
Ritchie, D. A.
Powiązania:
https://bibliotekanauki.pl/articles/2041625.pdf
Data publikacji:
2005-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Hb
72.50.+b
73.50.Rb
77.65.Dq
Opis:
Over the last few years we have developed a new method to control single-electrons by isolating and moving them through a submicron width channel formed in a GaAs/AlGaAs heterostructure using a surface acoustic wave. The acoustic wave acts to push electrons through the depleted submicron channel in packets each containing an integer number of electrons. Our primary motivation for studying this system has been to develop a new standard of dc current for metrological purposes, but our recent focus has widened to investigate the possibility of single-photon emission. Here we show new experimental results which demonstrate acoustoelectric current flow in adjacent 1D wires. These results have relevance both to the use of the system in a single-photon emission scheme, as well as in the creation of a proposed acoustoelectric quantum computer.
Źródło:
Acta Physica Polonica A; 2005, 107, 1; 38-45
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Space Description of Localization in Disordered One-Dimensional Systems
Autorzy:
Wołoszyn, M.
Spisak, B. J.
Maksymowicz, A. Z.
Powiązania:
https://bibliotekanauki.pl/articles/2047103.pdf
Data publikacji:
2006-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Hb
73.20.Fz
71.23.An
Opis:
The degree of electronic localization in disordered one-dimensional systems is discussed. The model is simplified to a set of Diracδ-like functions used for the potential in the Schrödinger equation and calculations are carried out for the ground state. The disorder of topological character is introduced by the random shifts of the potential peaks. For comparison, we also discuss two aperiodic systems of the potential peaks: Thue-Morse and Fibonacci sequences. The localization, both in the momentum and the real space, is analyzed for different disorder strengths and sizes of the system. We calculate the localization length, and additionally we express the localization effects in terms of the inverse participation function and also by means of the Husimi quasi-classical distribution function in the phase space of the electron (position, momentum) coordinate system. We present the influence of disorder generated by the random and aperiodic sequences of potential on the energy spectrum.
Źródło:
Acta Physica Polonica A; 2006, 110, 4; 523-535
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ballistic Transport Phenomena in Nanostructures of Paraelectric Lead Telluride
Autorzy:
Grabecki, G.
Powiązania:
https://bibliotekanauki.pl/articles/2047366.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Jc
73.21.Hb
73.23.Ad
77.22.Ch
Opis:
This is a review of our recent developments in the physics of lead telluride nanostructures. PbTe is a IV-VI narrow gap paraelectric semiconductor, characterized by the huge static dielectric constant ε >1000 at helium temperatures. We nanostructurized this material by means of e-beam lithography and wet chemical etching of modulation doped PbTe/Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te quantum wells. Magnetoresistance measurements performed on the nano-structures revealed a number of magnetosize effects, confirming a ballistic motion of the carriers. The most important observation is that the conductance of narrow constrictions shows a precise zero-field quantization in 2e$\text{}^{2}$/h units, despite a significant amount of charged defects in the vicinity of the conducting channel. This unusual result is a consequence of a strong suppression of the Coulomb potential fluctuations in PbTe, an effect confirmed by numerical simulations. Furthermore, the orbital degeneracy of electron waveguide modes can be controlled by the width of PbTe/Pb$\text{}_{1-x}$Eu$\text{}_{x}$Te quantum wells, so that unusual sequences of plateau conductance can be observed. Finally, conductance measurements in a nonlinear regime allowed for an estimation of the energy spacing between the one-dimensional subbands.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 127-139
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:
Modeling of Small Diameter Semiconductor Nanowires
Autorzy:
Bukała, M.
Galicka, M.
Buczko, R.
Kacman, P.
Powiązania:
https://bibliotekanauki.pl/articles/2047717.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Hb
73.43.Cd
73.61.Ey
Opis:
The properties of very thin (up to 16Å diameter) wires, cut out from the bulk in either zinc-blende or wurtzite material, are studied theoretically. In the total energy calculations we use ab initio methods and consider three different crystallographic growth axes for the zinc-blende and one for the wurtzite structure. We show that the most stable zinc-blende nanowires are those growing along (111) direction, however, the wurtzite structure is found to be energetically more favorable than the zinc-blende for wires of the same diameter. In addition, the band structure of the wires was calculated.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 425-430
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conductance Quantization in the Melt-Spun Cubic $RCu_5$ (R = Gd, Ho, Lu) Nanowires
Autorzy:
Szorcz, M.
Susła, B.
Wawrzyniak, M.
Lipiński, S.
Idzikowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/1810416.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.Ad
73.21.Hb
73.63.Rt
Opis:
Conductance quantization of heterocontacts between tungsten (W) tip and cubic $RCu_5$ (R = Gd, Ho, Lu) binary compounds prepared by melt-spinning was observed in nanowires produced dynamically using piezoelectric actuator. The conductance stepwise behaviour of the nanowires was directly observed with a storage oscilloscope. Quantum units of the nanowires conductance measured in their paramagnetic states are presented and discussed in terms of the Landauer formalism.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 165-167
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:
Intersubband Absorption in Quantum Dash Nanostructures
Autorzy:
Crnjanski, J.
Gvozdić, D.
Powiązania:
https://bibliotekanauki.pl/articles/1795640.pdf
Data publikacji:
2009-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Hb
78.67.Lt
78.67.Uh
Opis:
The band structure and corresponding intersubband absorption coefficient of quantum dash structures are modeled using a self-consistent single-band effective-mass approach and dipole approximation. Size fluctuation of the quantum dash ensemble, described with Gaussian distribution, is included in the model and its effects on the absorption spectrum are analyzed. The profile of the absorption spectrum is suitable for fitting with a sum of Gaussian functions. We find that the quantum dash ensemble has a pronounced and broad absorption spectrum in mid-infrared region, which becomes broader and more asymmetric with increase of the size fluctuation. In addition, for very large size fluctuation, the spectrum becomes flattened in relatively wide wavelength range.
Źródło:
Acta Physica Polonica A; 2009, 116, 4; 668-671
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Conductivity in Open Cylindrical Two-Barrier Symmetric Resonance Tunnel Structure
Autorzy:
Tkach, M.
Makhanets, O.
Seti, Ju.
Dovganiuk, M.
Voitsekhivska, O.
Powiązania:
https://bibliotekanauki.pl/articles/1537805.pdf
Data publikacji:
2010-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Hb
73.21.La
73.40.Gk
Opis:
The theory of resonance energies and widths of electron quasi-stationary states and electronic conductivity in open cylindrical two-barrier symmetric resonance tunnel structure is developed. The complete Schrodinger equation is solved within the model of effective masses for rectangular potential wells and barriers. Interaction between electrons and electromagnetic field was taken into account using the approximation of the small signal. The calculations of spectral parameters are performed for $In_{0.53}Ga_{0.47}As$/$In_{0.52}Al_{0.48}As$ resonance tunnel structure. The dependences of conductivity on the energy of mono-energy electrons beam falling at the system and electromagnetic field energy absorbed or emitted by the system are obtained and analyzed. The relation between experimentally measured parameters of conductivity and resonance widths of electron quasi-stationary states in open resonance tunnel structure is established.
Źródło:
Acta Physica Polonica A; 2010, 117, 6; 965-970
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Capacitance-Voltage Studies of Ti/p-ZnTe Schottky Barrier Structures Containing CdTe Quantum Dots
Autorzy:
Placzek-Popko, E.
Szatkowski, J.
Zielony, E.
Gumienny, Z.
Dobaczewski, L.
Karczewski, G.
Powiązania:
https://bibliotekanauki.pl/articles/2048047.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ga
73.21.La
73.20.Hb
Opis:
In this paper the electronic states of self-organized CdTe quantum dots embedded in ZnTe matrix are studied by means of capacitance-voltage (C-V) characteristics within the temperature range of 180-300 K. A reference diode of the same layer structure but without quantum dots is studied also for comparison. The C-V characteristics measured for the reference diode exhibit bulk behaviour in contrast to the quantum dots sample for which a characteristic step corresponding to discharging of quantum dots is clearly visible within broad range of temperatures. A quasistatic model based on the self-consistent solution of the Poisson equations is used to simulate the capacitance. By comparison the calculated C-V curve with experimental curve the apparent thermal activation energy for hole emission from the quantum dots to the ZnTe matrix is found to be equal to (0.12 ± 0.03) eV.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 621-623
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deep Levels Induced by CdTe/ZnTe Quantum Dots
Autorzy:
Zielony, E.
Placzek-Popko, E.
Roznicka, A.
Gumienny, Z.
Szatkowski, J.
Dyba, P.
Pacuski, W.
Kruse, C.
Hommel, D.
Guziewicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/2048061.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ga
73.21.La
73.20.Hb
Opis:
The electrical properties of the CdTe/ZnTe quantum dot system have been analyzed to identify deep-level defects related with the presence of quantum dots. The capacitance-voltage (C-V) and deep level transient spectroscopy measurements were used to investigate the samples. A reference ZnTe sample (without dots) was also studied for comparison. Both samples were grown by molecular beam epitaxy technique on the n-type GaAs substrate. The quantum dots were formed by a Zn-induced reorganization of a thin CdTe layer. The presence of quantum dot formation was confirmed by micro-photoluminescence measurements. The deep level transient spectra for both samples are complex. In order to characterize individual contributions to the deep level transient spectra the latter have been simulated by separated Gaussian components [1]. The results of the deep level transient spectroscopy measurements yield the conclusion that the same defects are present in both materials but there is an increased concentration of the defects in the quantum dot structures. No deep level associated directly with the quantum dot confinement has been identified.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 630-632
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrical Characterizations of Schottky Diodes οn ITO Modified by Aromatic SAMs
Autorzy:
Havare, A.
Okur, S.
Yagmurcukardes, N.
Can, M.
Aydin, H.
Seker, M.
Demic, S.
Powiązania:
https://bibliotekanauki.pl/articles/1400033.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Hb
73.20.Mf
73.21.-b
73.22.-f
73.25.+i
73.40.Ei
73.40.Jn
73.40.Ns
Opis:
In order to understand the electronic properties of the organic Schottky diode, ITO/TPD/Al and ITO/SAM/TPD/Al organic Schottky devices were fabricated to obtain current-voltage characteristics. From the slopes and y-axis intercepts of the plots, the values of the ideality factor, barrier heights of the ITO/SAM/TPD/Al diode were determined as 2.03 and 0.56 eV, respectively. The surface characterizations of modified and unmodified ITO were performed via atomic force microscopy.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 456-458
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lateral Coupling within the Ensemble of InAs/InGaAlAs/InP Quantum Dashes
Autorzy:
Ryczko, K.
Sęk, G.
Misiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/1399089.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
73.21.Hb
78.67.Uh
Opis:
In this work we investigate the electronic structure of coupled quantum dashes. The respective confined state energy levels are calculated for various cross-sectional shapes and sizes of the dashes and in function of the lateral distance between them. The results are confronted with the existing experimental data on the optical transitions in such structures. It has been concluded that for realistic system parameters (geometry and spatial in-plane separation) the obtained direct coupling is weak and in most of the applications the dashes can be considered individually, as long as the ensemble is strongly inhomegeneous.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 805-808
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$D_2^+$ Molecular Complex in Ring-Like Nanostructures: Hydrostatic Pressure and Electromagnetic Field Effects
Autorzy:
Fulla, M.
Marín, J.
Gutiérrez, W.
Duque, C.
Mora-Ramos, M.
Powiązania:
https://bibliotekanauki.pl/articles/1215648.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
73.20.Hb
73.21.La
Opis:
In this work we investigate the energy states in a $D_2^+$ complex formed by the coupling of a conduction band electron and two donor centers in a quantum ring with rectangular cross-section. The influences of externally applied probes like electric and magnetic fields and hydrostatic pressure together with the change in the relative position between the two Coulombic centers are particularly studied, highlighting the important contribution of the repulsive inter-center interaction. The destruction of the Aharonov-Bohm oscillations of the ground state associated with the localization of the electron states in the system is discussed.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 241-244
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Double-Donor Energy Structure in Concentric Quantum Rings under Magnetic Field and Hydrostatic Pressure
Autorzy:
Fulla, M.
Marín, J.
Londoño, D.
Duque, C.
Mora-Ramos, M.
Powiązania:
https://bibliotekanauki.pl/articles/1194836.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
73.20.Hb
73.21.La
Opis:
A model for an artificial hydrogen molecule consisting of two positive on-axis Coulombic centers and two electrons coupled to them inside a double concentric quantum ring is considered. Such a nanostructure is assumed to be under the influence of external probes like hydrostatic pressure and magnetic field. By using the adiabatic approximation, the ground state energy is calculated as a function of the outer center line radius and the impurity Coulombic center separation, for different values of the hydrostatic pressure and magnetic field strength. In contrast to the single properties imposed by nature on the actual hydrogen molecule, our model allows us to explore a great variety of properties of the artificial hydrogen molecule by changing the ring dimensions. The artificial hydrogen molecule energy structure may be tuned by changing the external field strengths.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 220-223
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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