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1

Application of the Picosecond Magnetic Pulses for Inducing the Electron Motion in the Bilayer Nanowire

100%

Chwiej T.

Acta Physica Polonica A

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2016

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vol. 130

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issue 5

1217-1219

EN

We theoretically study the effects of interaction of the single electron confined in a piece of bilayer nanowire with the picosecond magnetic pulse. It is shown that the transverse time-varying magnetic field hybridizes temporarily the vertical modes in the electron wave function which eventually stimulates its motion along the wire axis. The dynamics of such magnetically driven motion depends on the geometry of the confining potential, the effective mass of the electron and the time duration of the magnetic pulse. We show that this effect can potentially be utilized for fabrication of the magnetic valve.

2

Ballistic Transport Phenomena in Nanostructures of Paraelectric Lead Telluride

80%

Grabecki G.

Acta Physica Polonica A

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2007

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vol. 112

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issue 2

127-139

EN

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_{1-x}Eu_xTe 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^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_{1-x}Eu_xTe 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.

3

Intersubband Absorption in Quantum Dash Nanostructures

80%

Crnjanski J., Gvozdić D.

Acta Physica Polonica A

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2009

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vol. 116

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issue 4

668-671

EN

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.

4

Electronic Conductivity in Open Cylindrical Two-Barrier Symmetric Resonance Tunnel Structure

80%

Tkach M., Makhanets O., Seti J., Dovganiuk M., Voitsekhivska O.

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issue 6

965-970

EN

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.

5

Lateral Coupling within the Ensemble of InAs/InGaAlAs/InP Quantum Dashes

80%

Ryczko K., Sęk G., Misiewicz J.

Acta Physica Polonica A

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2013

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vol. 124

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issue 5

805-808

EN

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.

6

Phase Space Description of Localization in Disordered One-Dimensional Systems

80%

Wołoszyn M., Spisak B., Maksymowicz A.

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EN

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.

7

Modeling of Small Diameter Semiconductor Nanowires

80%

Bukała M., Galicka M., Buczko R., Kacman P.

Acta Physica Polonica A

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2007

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vol. 112

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issue 2

425-430

EN

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.

8

Acoustic Transport of Electrons in Parallel Quantum Wires

80%

Cunningham J., Pepper M., Talyanskii V., Ritchie D.

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EN

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.

9

Conductance Quantization in the Melt-Spun Cubic RCu_5 (R = Gd, Ho, Lu) Nanowires

80%

Szorcz M., Susła B., Wawrzyniak M., Lipiński S., Idzikowski B.

Acta Physica Polonica A

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2009

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vol. 115

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issue 1

165-167

EN

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.

10

Mechanical and Electrical Properties, of ZnO-Nanowire/Si-Substrate Junctions Studied by Scanning Probe Microscopy

70%

Aleszkiewicz M., Fronc K., Wróbel J., Klepka M., Wojtowicz T., Karczewski G.

Acta Physica Polonica A

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2007

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vol. 112

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issue 2

255-260

EN

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.

Refine search results

Application of the Picosecond Magnetic Pulses for Inducing the Electron Motion in the Bilayer Nanowire

Ballistic Transport Phenomena in Nanostructures of Paraelectric Lead Telluride

Intersubband Absorption in Quantum Dash Nanostructures

Electronic Conductivity in Open Cylindrical Two-Barrier Symmetric Resonance Tunnel Structure

Lateral Coupling within the Ensemble of InAs/InGaAlAs/InP Quantum Dashes

Phase Space Description of Localization in Disordered One-Dimensional Systems

Modeling of Small Diameter Semiconductor Nanowires

Acoustic Transport of Electrons in Parallel Quantum Wires

Conductance Quantization in the Melt-Spun Cubic RCu_5 (R = Gd, Ho, Lu) Nanowires

Mechanical and Electrical Properties, of ZnO-Nanowire/Si-Substrate Junctions Studied by Scanning Probe Microscopy