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Tytuł:
Simulating the Electron Transmission with Different Defective Carbon Nanotubes
Autorzy:
Nizam, R.
Rizvi, S.
Azam, A.
Powiązania:
https://bibliotekanauki.pl/articles/1419854.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
Opis:
2. The transmissions of forty-eight carbon nanotube geometries to form twenty-four intramolecular junctions between every two carbon nanotubes and two simple carbon nanotubes are also taken for investigating numerically. These forty-eight carbon nanotubes form three different kinds of intramolecular junctions, which mean that each sixteen carbon nanotubes are identical to either sixteen carbon nanotubes in all respect, except three different intramolecular junctions in between them. The three intramolecular junctions, named as circumferential defective carbon nanotubes, grouped defective carbon nanotubes and distributed defective carbon nanotubes. The nature of electronic states at the interfaces and in the semiconductor section is analyzed with the help of tight-binding method. These quantum transmissions have been compared among the different defective carbon nanotubes and have been correlated with the pentagon and heptagon that formed in the intramolecular junction. It has been simulated that each pair of semiconductor-semiconductor carbon nanotubes, semiconductor-metallic carbon nanotubes and metallic-metallic carbon nanotubes transmission affect on the presence of junctions pentagons-heptagons. The least deviations transmission is observed in the circumferential defective carbon nanotubes rather than in other two and the maximum deviations are seen in the grouped defective carbon nanotubes irrespective of the joining of the carbon nanotube interface.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 190-196
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface Plasmon Frequency Spectrum in a System of Two Spherical Dielectric Coated Metallic Nanoparticles
Autorzy:
Makaryan, T.
Melikyan, A.
Minassian, H.
Powiązania:
https://bibliotekanauki.pl/articles/2047874.pdf
Data publikacji:
2007-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
Opis:
Semi-analytical method of surface plasmon frequency calculation for the system of two almost touching coupled dielectric coated metallic nanospheres is presented. The method allows transforming the problem to numerical solution of two simple algebraic equations for arbitrary values of parameters - particle radius, distance between sphere centers, dielectric permittivity of the matrix, dielectrics and metals. It is especially easy to get the obvious graphical solution. The surface plasmon frequencies of longitudinal and transversal oscillations of the system are calculated and good agreement with the experimental results is achieved.
Źródło:
Acta Physica Polonica A; 2007, 112, 5; 1025-1029
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Friedel Oscillations in Carbon Nanotube Quantum Dots and Superlattices
Autorzy:
Chico, L.
Santos, H.
Ayuela, A.
Pelc, M.
Jaskólski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1811922.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
73.90.+f
Opis:
Interface states of all-metallic carbon nanotube quantum dots and superlattices are studied within a tight-binding model. We focus on achiral systems made by connecting armchair (n,n) and zigzag (2n,0) tubes with a full ring of n pentagon-heptagon topological defects. We show that the coupling between interface states, which arise from the topological defects, reflects the existence of the Friedel oscillations in the (n,n) tube, with an unusually large decay exponent. We expect this interaction to be important for the understanding of other physical properties, such as selective dot growth, magnetic interaction through carbon tubes or optical spectroscopy of interface states.
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1085-1091
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Transmission through Graphene Bilayer Flakes
Autorzy:
Chico, L.
González, J.
Santos, H.
Pacheco, M.
Brey, L.
Powiązania:
https://bibliotekanauki.pl/articles/1419511.pdf
Data publikacji:
2012-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
73.63.-b
Opis:
We investigate the electronic transport properties of a bilayer graphene flake contacted by two monolayer nanoribbons. This finite-size bilayer flake can be built by overlapping two semi-infinite ribbons. We study and analyze the electronic behavior of this structure by means of a tight-binding method and a continuum Dirac model. We have found that the conductance oscillates markedly between zero and the maximum value of the conductance, allowing for the design of electromechanical switches.
Źródło:
Acta Physica Polonica A; 2012, 122, 2; 299-303
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Collective Phenomena in Multiwall Carbon Nanotubes
Autorzy:
Margańska, M.
Szopa, M.
Zipper, E.
Powiązania:
https://bibliotekanauki.pl/articles/2038389.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
73.23.Ra
Opis:
Collective phenomena due to persistent currents in carbon multiwall nanotubes are studied. The formula for persistent currents minimising free energy and conditions for the stability of persistent currents in multiwall nanotubes in magnetic field are derived. Numerical calculations performed show the possibility of obtaining spontaneous currents in two optimal configurations: undoped armchair-only multiwall nanotubes up to 0.01 K, and zig-zag-chiral-chiral-zig-zag multiwall nanotubes doped to -3.033 eV up to about 1 K. The latter configuration may exhibit also the diamagnetic expulsion of magnetic field, which according to our calculations can reach 20% of the external flux.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 609-616
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Band Structure and Quantum Conductance of Metallic Carbon Nanotube Superlattices
Autorzy:
Jaskólski, W.
Stachów, A.
Chico, L.
Powiązania:
https://bibliotekanauki.pl/articles/2043721.pdf
Data publikacji:
2005-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
73.63.-b
Opis:
The electronic structure and quantum conductance of rotationally invariant (6,6)/(12,0) and rotationally non-invariant (5,5)/(8,2) superlattices made of metallic carbon nanotubes are investigated. It is shown that, except in the limit of very large periods, the quantum conductance of such superlattices does not critically depend on their rotational invariance, although it does in case of quantum dots and single junctions made of these nanotubes.
Źródło:
Acta Physica Polonica A; 2005, 108, 4; 697-704
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport and Capacitance Spectroscopy of Quantum Dots
Autorzy:
Adamowski, J.
Bednarek, S.
Szafran, B.
Powiązania:
https://bibliotekanauki.pl/articles/2027454.pdf
Data publikacji:
2001-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
73.63.-b
Opis:
A review of recent theoretical studies on a single-electron tunneling in quantum dots is presented. This effect underlies the transport spectroscopy performed on the vertical gated quantum dots and the capacitance spectroscopy on the self-assembled quantum dots. The conditions of the single-electron tunneling are formulated in terms of electrochemical potentials of the electrons in the leads and in the quantum dot. The electrochemical potentials for the electrons confined in the quantum dots can be calculated by solving the many-electron Schrödinger equation. The results obtained by the Hartree-Fock method are presented. For the vertical gated quantum dot, the realistic confinement potential is obtained from the Poisson equation. The application of the self-consistent procedure to the solution of the Poisson-Schrödinger problem is discussed. The calculated positions of the current peaks at zero bias and boundaries of the Coulomb diamonds for non-zero bias are in good agreement with experiment. The influence of an external magnetic field on the single-electron tunneling is also discussed. The spin-orbital configurations of the electrons confined in the quantum dots change with the magnetic field, which leads to features observed in the current-voltage and capacitance-voltage characteristics.
Źródło:
Acta Physica Polonica A; 2001, 100, 2; 145-163
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hole Subband Mixing and Polarization of Luminescence from Quantum Dashes: A Simple Model
Autorzy:
Kaczmarkiewicz, P.
Musiał, A.
Sęk, G.
Podemski, P.
Machnikowski, P.
Misiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/2048063.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.Hc
73.22.-f
Opis:
In this paper, we address the problem of luminescence polarization in the case of nanostructures characterized by an in-plane shape asymmetry. We develop a simple semi-qualitative model revealing the mechanism that accounts for the selective polarization properties of such structures. It shows that they are not a straightforward consequence of the geometry but are related to it via valence subband mixing. Our model allows us to predict the degree of polarization dependence on the in-plane dimensions of investigated structures assuming a predominantly heavy hole character of the valence band states, simplifying the shape of confining potential and neglecting the influence of the out-of-plane dimension. The energy dependence modeling reveals the importance of different excited states in subsequent spectral ranges leading to non-monotonic character of the degree of polarization. The modeling results show good agreement with the experimental data for an ensemble of InAs/InP quantum dashes for a set of realistic parameters with the heavy-light hole states separation being the only adjustable one. All characteristic features are reproduced in the framework of the proposed model and their origin can be well explained and understood. We also make some further predictions about the influence of both the internal characteristics of the nanostructures (e.g. height) and the external conditions (excitation power, temperature) on the overall degree of polarization.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 633-636
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Correlations in Hexagonal Lattice Systems - Application to Carbon Nanotubes
Autorzy:
Czajka, K.
Maśka, M. M.
Powiązania:
https://bibliotekanauki.pl/articles/2041458.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
71.15.Dx
Opis:
We present exact diagonalization studies of two-dimensional electron gas on hexagonal lattice. Using Lanczös method we analyze the influence of the Coulomb correlations on the density of states and spectral functions. Choosing appropriate boundary conditions we simulate the geometry of a single wall carbon nanotube. In particular, integration over the boundary condition in one direction and summation in the other one allows us to perform cluster calculations for a tube-like system with a finite diameter and infinite length.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 703-707
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Valence Band Modifications on Hydrogen Absorption in Zr-Pd Alloy Thin Films
Autorzy:
Jabłoński, B.
Pacanowski, S.
Werwiński, M.
Marczyńska, A.
Dawczak-Dębicki, H.
Szajek, A.
Smardz, L.
Powiązania:
https://bibliotekanauki.pl/articles/1030742.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
82.80.Pv
Opis:
We study the valence band modifications of in-situ prepared nano- and polycrystalline Pd-Zr alloy thin films using X-ray photoelectron spectroscopy. Results were compared with valence bands calculated by ab initio methods. Furthermore, hydrogen absorption and desorption kinetics under pressure of about 570 mbar were studied in Pd covered nanocrystalline ZrPd₂ alloy thin film. Results showed that modifications of the valence band of the nanocrystalline alloy thin film could significantly influence on hydrogen absorption and desorption process.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 620-623
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
XPS Valence Band Studies of $LaNi_{5-x}Mₓ$ (M = Al, Co; x = 0, 1) Alloy Thin Films
Autorzy:
Skoryna, J.
Marczyńska, A.
Pacanowski, S.
Szajek, A.
Smardz, L.
Powiązania:
https://bibliotekanauki.pl/articles/1386422.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
71.20.-b
Opis:
$LaNi_{5-x}Mₓ$ (M = Al, Co) alloy thin films were prepared onto oxidised Si(100) substrates in the temperature range of 285-700 K using UHV magnetron co-sputtering. The surface chemical composition and valence bands of all the alloy thin films were measured in situ, immediately after deposition, transferring the samples to an UHV analysis chamber equipped with X-ray photoelectron spectroscopy. Results showed that the shape of the valence bands measured for the polycrystalline samples is practically the same compared to those obtained theoretically from ab initio band structure calculations. On the other hand, the X-ray photoelectron spectroscopy valence bands of the nanocrystalline thin films (especially LaNi₄Co) are considerably broader compared to those measured for the polycrystalline samples. This is probably due to a strong deformation of the nanocrystals. Therefore, the different microstructure observed in polycrystalline and nanocrystalline alloy thin films leads to significant modifications of their electronic structure.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 430-432
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Properties of In Situ Prepared Nanocrystalline Fe-Ni-Ti Alloy Thin Films
Autorzy:
Pacanowski, S.
Skoryna, J.
Marczyńska, A.
Skoryna, D.
Smardz, L.
Powiązania:
https://bibliotekanauki.pl/articles/1386482.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
68.55.-a
Opis:
In this contribution we study experimentally the electronic properties of nanocrystalline Fe-Ni-Ti alloy thin films using X-ray photoelectron spectroscopy. The structure of the samples has been studied by X-ray diffraction. Their bulk chemical compositions were measured using X-ray fluorescence method. The surface chemical composition and the cleanness of all samples were checked in situ, immediately after deposition, transferring the samples to an UHV analysis chamber equipped with X-ray photoelectron spectroscopy. X-ray diffraction studies revealed the formation of nanocrystalline Fe-Ni-Ti alloy thin films at a substrate temperature of about 293 K. In situ X-ray photoelectron spectroscopy studies showed that the valence bands of nanocrystalline samples are broader compared to those measured for the polycrystalline bulk alloys. Such modifications of the valence bands of the nanocrystalline alloy thin films could influence on their hydrogenation properties.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 436-438
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Shells of Dirac Fermions in Graphene Quantum Rings in a Magnetic Field
Autorzy:
Potasz, P.
Güçlü, A.
Hawrylak, P.
Powiązania:
https://bibliotekanauki.pl/articles/1791290.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
81.07.Ta
Opis:
We present results of tight binding calculations demonstrating existence of degenerate electronic shells of Dirac fermions in narrow, charge neutral graphene quantum rings. We predict removal of degeneracy with finite magnetic field. We show, using a combination of tight binding and configuration interaction methods, that by filling a graphene ring with additional electrons this carbon based structure with half-filled shell acquires a finite magnetic moment.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 832-834
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zero-Bias Anomaly in Magnetic Tunnel Junctions
Autorzy:
Yang, H.
Yang, S.
Ilnicki, G.
Martinek, J.
Parkin, S.
Powiązania:
https://bibliotekanauki.pl/articles/1536909.pdf
Data publikacji:
2010-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.La
73.23.-b
73.22.-f
Opis:
We present experimental results, which may indicate the possibility of the coexistence of the Kondo effect and ferromagnetism in macroscopic planar magnetic tunnel junctions with a layer of nanodots inside tunnel barriers. A conductance double peak structure was observed. Magnetic field dependence of the splitting of a conductance peak, and temperature evolution of the conductance curves are well explained from the theoretical point of view according to the predictions of the Kondo physics and cotunneling in the Anderson quantum dot coupled to ferromagnetic leads.
Źródło:
Acta Physica Polonica A; 2010, 118, 2; 316-318
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cotunneling Transport at Singlet-Triplet Transition in Carbon Nanotube Quantum Dots
Autorzy:
Ilnicki, G.
Moriyama, S.
Martinek, J.
Fuse, T.
Ishibashi, K.
Powiązania:
https://bibliotekanauki.pl/articles/1810544.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
73.23.Hk
73.63.Fg
Opis:
Electronic transport through a quantum dot in the Coulomb-blockade cotunelling regime is investigated both experimentally and theoretically, where a single-wall carbon-nanotube weakly coupled to metallic leads plays a role of the dot. We observe a pronounced current peak for the singlet-triplet transition in a half-shell filling regime due to inelastic cotunneling processes. Using the second order perturbation theory we explain physical mechanisms determining the details of signal.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 299-302
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin-Dependent Transport through SU(4) Kondo Dot in the Presence of Spin-Flip Processes
Autorzy:
Krychowski, D.
Lipiński, S.
Powiązania:
https://bibliotekanauki.pl/articles/1534863.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
73.23.-b
73.63.Fg
Opis:
The spin-resolved current of carbon nanotube quantum dot coupled to ferromagnetic electrodes and influenced by spin-flip scattering is studied in the Kondo regime by the equation of motion method.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 955-956
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of the Dot-Ring Nanostructure to Control Electrical Transport in the Coulomb Blockade Regime
Autorzy:
Janus-Zygmunt, I.
Kędzierska, B.
Gorczyca-Goraj, A.
Kurpas, M.
Maśka, M.
Zipper, E.
Powiązania:
https://bibliotekanauki.pl/articles/1376091.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.Hk
73.21.La
73.22.-f
Opis:
Transport properties of a two-dimensional nanostructure composed of a quantum dot surrounded by a quantum ring (dot-ring nanostructure), are discussed. This complex system is a highly controllable object. Conduction through dot-ring nanostructure depends crucially on the coupling strength of its states to the electrodes, which is related to the spatial distribution of the electron's wave functions in dot-ring nanostructure. This distribution can be strongly modified, e.g., by the electrical gating so that the ground and excited states move between the inner dot and the outer ring. In this paper we show that this property can be used to control single-electron DC current through dot-ring nanostructure in the Coulomb blockade regime so that it can be used as a single electron transistor.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1171-1173
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kondo Effect in Carbon Nanotube Quantum Dot in a Magnetic Field
Autorzy:
Krychowski, D.
Lipiński, S.
Powiązania:
https://bibliotekanauki.pl/articles/1810539.pdf
Data publikacji:
2009-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
73.23.-b
73.63.Fg
Opis:
The out-of-equilibrium electron transport of carbon nanotube semiconducting quantum dot placed in a magnetic field is studied in the Kondo regime by means of the non-equilibrium Green functions. The equation of motion method is used. For parallel magnetic field the Kondo peak splits into four peaks, following the simultaneous splitting of the orbital and spin states. For perpendicular field orientation the triple peak structure of density of states is observed with the central peak corresponding to orbital Kondo effect and the satellites reflecting the spin and spin-orbital fluctuations.
Źródło:
Acta Physica Polonica A; 2009, 115, 1; 293-295
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multiband Electronic Structure of Magnetic Quantum Dots: Numerical Studies
Autorzy:
Rederth, D.
Oszwałdowski, R.
Petukhov, A.
Pientka, J.
Powiązania:
https://bibliotekanauki.pl/articles/1029747.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.La
73.22.-f
75.50.Pp
Opis:
Semiconductor quantum dots (QDs) doped with magnetic impurities have been a focus of continuous research for a couple of decades. A significant effort has been devoted to studies of magnetic polarons (MP) in these nanostructures. These collective states arise through exchange interaction between a carrier confined in a QD and localized spins of the magnetic impurities (typically: Mn). Our theoretical description of various MP properties in self-assembled QDs is discussed. We present a self-consistent, temperature-dependent approach to MPs formed by a valence band hole. The Luttinger-Kohn k· p Hamiltonian is used to account for the important effects of spin-orbit interaction.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 343-349
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Structure of Elongated $In_{0.3}Ga_{0.7}As//GaAs$ Quantum Dots
Autorzy:
Pieczarka, M.
Musiał, A.
Podemski, P.
Sęk, G.
Misiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/1399091.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.Hc
73.21.La
73.22.-f
Opis:
In this contribution the electronic structure of large $In_{0.3}Ga_{0.7}As//GaAs$ quantum dots is studied theoretically by means of 8 band k · p modeling. These quantum dots constitute unique physical system due to the low strain limit of the Stranski-Krastanow growth mode resulting in relatively large physical volume and elongation of the quantum dots in [1-10] direction. As a result of these critical growth conditions the electronic structure is expected to be very sensitive to the nanostructure size, shape, and composition of the quantum dot as well as the accompanying wetting layer. Another peculiarity of investigated system is the confining potential which is rather shallow and weakened in comparison to standard quantum dots. It makes them very interesting in view of both fundamental study and potential applications. To reveal physical mechanisms determining the optical properties of the investigated system, the electronic structure, mainly the number of confined states, and the wave function extension as a function of both quantum dot size and geometry have been simulated numerically and the importance of electron-hole Coulomb interactions has been evaluated.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 809-812
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metastability of Band-Gap Energy in GaInNAs Compound Investigated by Photoreflectance
Autorzy:
Kudrawiec, R.
Misiewicz, J.
Pavelescu, E.-M.
Konttinen, J.
Pessa, M.
Powiązania:
https://bibliotekanauki.pl/articles/2038258.pdf
Data publikacji:
2004-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.22.-f
78.66.-w
78.30.-j
Opis:
The band-gap energy of GaInNAs layers lattice-matched to GaAs substrate and annealed under different temperatures is investigated by photoreflectance spectroscopy. Different nitrogen nearest-neighbor environments of N atom appear in GaInNAs layers due to the post-growth annealing. It leads to an energy-fine structure of the band gap, i.e. well separated photoreflectance resonances related to different nitrogen nearest-neighbor environments (N-Ga$\text{}_{4-m}$In$\text{}_{m}$ (0≤ m≤ 4) short-range-order clusters). The temperature dependence of the band gap E(T) related to different N-Ga$\text{}_{4-m}$In$\text{}_{m}$ clusters is investigated in 10-280 K temperature range, and Varshni and Bose-Einstein parameters for E(T) are determined.
Źródło:
Acta Physica Polonica A; 2004, 106, 2; 249-263
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure and Energetics of Fragments of the Planar α and β Boron Sheets
Autorzy:
Gonzalez Szwacki, N.
Tarkowski, T.
Majewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1398547.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.-w
68.65.-k
73.22.-f
Opis:
Large scale first principles calculations based on density functional theory and using hybrid exchange-correlation functionals have been performed in order to study the structural properties and the relative stability of fragments of the planar α and β boron sheets. Based on the considered structures, we show that, in contrast to the fragments of the α -sheet, all the fragments of the β -sheet, having more than ≈30 atoms, are fully planar regardless of their shape. We conclude that the β -sheet is the only planar boron sheet reported so far that retains planarity even if it is reduced to relatively small fragments.
Źródło:
Acta Physica Polonica A; 2016, 129, 1a; A-148-A-149
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Efficient Emission from InAlGaAs Single Quantum Dots with Low Lattice Misfit and AlGaAs Indirect Bandgap Barrier
Autorzy:
Słupiński, T.
Korona, K.
Papierska, J.
Borysiuk, J.
Powiązania:
https://bibliotekanauki.pl/articles/1398581.pdf
Data publikacji:
2016-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
73.22.-f
78.47.jd
Opis:
We report on molecular beam epitaxy growth and properties of rarely studied quaternary In_{0.4}(Al_{0.75}Ga_{0.25})_{0.6}As self-assembled quantum dots, which show strong and efficient emission of red light from single quantum dots. The increased yield is, among others, due to efficient energy transfer from indirect band-gap Al_{0.75}Ga_{0.25}As barriers. To maximize photon energy emitted from quantum dots, low In composition, x_{In} = 0.4 was applied, which also lowered the lattice misfit close to the limit of 2D/3D transition in the Stranski-Krastanov growth mode. Time-resolved micro-photoluminescence shows emission at 650-750 nm. Well-resolved single quantum dot photoluminescence lines (decay time of ≈ 1-2 ns) are observed despite a high concentration ≈ 3×10¹¹ cm¯² of quantum dots. We discuss this observation assuming newly a role of carriers or excitons diffusion/tunneling between quantum dots at high surface concentration of dots and a possible role of lattice disorder inside the dot on the exciton lifetime.
Źródło:
Acta Physica Polonica A; 2016, 130, 5; 1229-1232
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Band Structure of Coiled Carbon Nanotubes
Autorzy:
Milošević, I.
Damnjanović, M.
Powiązania:
https://bibliotekanauki.pl/articles/1503008.pdf
Data publikacji:
2011-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.48.De
73.22.-f
81.07.-b
Opis:
More than fifteen years have passed since the first report of experimental evidence of regularly coiled carbon nanotubes, but, the structure, formation mechanism and theoretical aspects of these nanotubes still remain unresolved. We propose model of hexagonal, helically coiled single wall carbon nanotubes, determine their line group symmetry and calculate electronic band structure of the relaxed configurations by means of fully symmetry adopted density functional tight binding method implemented into the POLSym code. Electrical properties of the straight and coiled carbon nanotubes of different chiralities are compared and analyzed.
Źródło:
Acta Physica Polonica A; 2011, 120, 2; 221-223
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoluminescence Dynamics of GaN/Si Nanowires
Autorzy:
Korona, K.
Zytkiewicz, Z.
Perkowska, P.
Borysiuk, J.
Binder, J.
Sobanska, M.
Klosek, K.
Powiązania:
https://bibliotekanauki.pl/articles/1403621.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Cr
73.22.-f
78.47.jd
Opis:
In this work we present analysis of carriers dynamics in samples of GaN nanowires grown on silicon. The samples exhibit bright luminescence of bulk donor-bound excitons at 3.472 eV, surface defect-bound excitons at 3.450 eV (SDX) and a broad (0.05 eV) band centered at 3.47 eV caused probably by single free exciton and bi-exciton recombination. The SDX emission has long lifetime τ = 0.6 ns at 4 K and can be observed up to 50 K. At higher temperatures luminescence is dominated by free excitons. The broad excitonic band is best visible under high excitation, and reveals fast, non-exponential dynamics. We present mathematical model assuming exciton-exciton interaction leading to the Auger processes. The model includes $n^2$ (Langevin) term and describes well the non-exponential dynamics of the excitonic band.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1001-1003
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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