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Wyświetlanie 1-15 z 48
Tytuł:
Electronic structure calculations of InP-based coupled quantum dot-quantum well structures
Autorzy:
Andrzejewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1160527.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.La
73.21.Fg
73.22.Dj
74.50.+r
Opis:
In this work we investigate the electronic structure of coupled 0D-2D nanostructures. The respective confined state energy levels in a quantum dot-quantum well system are calculated for various conduction band offsets - between the quantum dot and surrounding material. The calculated electron and hole energy levels with their wave functions allow determining if the wave functions are within the injector quantum well or within the quantum dot and if the carrier positions on the energy scale are appropriate from the point of view of a possible laser structure utilizing the so-called tunnel injection scheme. It is shown that for an adequate width of an injector quantum well and the conduction band offsets designing an optimal tunnel injection structure is possible.
Źródło:
Acta Physica Polonica A; 2016, 129, 1a; A-97-A-99
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the 2D quantum tunneling
Autorzy:
Mohammadpour, H.
Powiązania:
https://bibliotekanauki.pl/articles/1159450.pdf
Data publikacji:
2016-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.-d
72.10.Bg
72.80.Vp
72.90.+y
73.21.Fg
73.23.-b
73.23.Ad
73.40.Gk
Opis:
In this paper, we have solved a quantum tunneling problem for 2-dimensional systems, including electron gas and graphene. In spite of the one-dimensional scattering problems, in two dimensions, we observe phenomenon of tunneling at energies above the barrier. This effect is an analogue to the total internal reflection in optics. The scattering amplitudes inside the barrier region exhibit decaying behavior corresponding to optical evanescent-wave coupling, not only in energies below barrier height, but also above barrier. Velocity-selecting transmission, corresponding to angle-resolved beam filtering effect is one of the achievements of the paper. The famous Hartman effect which occurs normally at sub-barrier energies and has previously been studied for graphene is also addressed. The results manifest occurrence of the Hartman effect for over-barrier energies, as well.
Źródło:
Acta Physica Polonica A; 2016, 130, 3; 769-772
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Room Temperature Carrier Kinetics in the W-type GaInAsSb/InAs/AlSb Quantum Well Structure Emitting in Mid-Infrared Spectral Range
Autorzy:
Syperek, M.
Ryczko, K.
Dallner, M.
Dyksik, M.
Motyka, M.
Kamp, M.
Höfling, S.
Misiewicz, J.
Sęk, G.
Powiązania:
https://bibliotekanauki.pl/articles/1398579.pdf
Data publikacji:
2016-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Fg
78.47.D-
78.30.Fs
78.47.jg
78.55.Cr
78.67.De
Opis:
Room temperature carrier kinetics has been investigated in the type-II W-design $AlSb//InAs//Ga_{0.80}In_{0.20}As_{0.15}Sb_{0.85}//InAs//AlSb$ quantum well emitting in the mid-infrared spectral range (at 2.54 μ m). A time-resolved reflectance technique, employing the non-degenerated pump-probe scheme, has been used as a main experimental tool. Based on that, a primary carrier relaxation time of 2.3±0.2 ps has been found, and attributed to the initial carrier cooling process within the quantum well states, while going towards the ground state via the carrier-optical phonon scattering mechanism. The decay of a quasi-equilibrium carrier population at the quantum well ground states is primarily governed by two relaxation channels: (i) radiative recombination within distribution of spatially separated electrons and holes that occurs in the nanosecond time scale, and (ii) the hole tunnelling out of its confining potential, characterized by a 240±10 ps time constant.
Źródło:
Acta Physica Polonica A; 2016, 130, 5; 1224-1228
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrons in a Semiconductor Quantum Well of the Magnetic Tunneling Structure
Autorzy:
Szczepański, T.
Dugaev, V.
Powiązania:
https://bibliotekanauki.pl/articles/1402583.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.25.Dc
73.21.Fg
85.75.Mm
Opis:
We discuss the properties of resonant tunneling diode with resonant levels in the quantum well. The energy levels are formed inside the well as a consequence of quantization of the states between two potential barriers. We solved the Schrödinger equation for the multilayer structure and found the energy of resonant level as a function of the width of quantum well for different parameters of energy profile in the equilibrium. The results present the dependence of spin splitting in the quantum well of nonmagnetic semiconductor on the spin polarization of electrodes.
Źródło:
Acta Physica Polonica A; 2015, 128, 2; 222-224
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exciton Binding Energy and Oscillator Strength in a Shallow Quantum Well in an External Magnetic Field
Autorzy:
Zięba, P.
Piętka, B.
Łusakowski, J.
Tralle, I.
Powiązania:
https://bibliotekanauki.pl/articles/1402589.pdf
Data publikacji:
2015-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.Ji
75.75.-c
73.21.Fg
62.20.-x
Opis:
We discuss the influence of an external magnetic field on the exciton energy and the exciton oscillator strength in the shallow quantum wells. We include into consideration the Coulomb attraction between electron and hole, which is rarely taken into account. We self-consistently solve the Schrödinger equation to compare the obtained results with the experimental values.
Źródło:
Acta Physica Polonica A; 2015, 128, 2; 237-239
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crystal Orientation Dependence of the Fundamental Optical Transition in type-II W-Design Quantum Well Structures
Autorzy:
Ryczko, K.
Powiązania:
https://bibliotekanauki.pl/articles/1376073.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Fg
71.55.Eq
Opis:
Using a multiband k·p theory the band structure properties of type-II W-design AlSb/InAs/GaInSb/InAs/AlSb quantum wells on GaSb substrates of various crystallographic orientations have been investigated. Such structures are predicted for the emission in a broad range of mid infrared from below 3 μm to beyond 10 μm. The energy of the fundamental optical transition and the corresponding oscillator strength have been determined in function of the layer structure details and versus the substrate orientation. In addition, the resulting optical anisotropy in such type-II quantum wells has been derived.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1149-1153
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polarization-Induced Band Inversion in In-Rich InGaN/GaN Quantum Wells
Autorzy:
Łepkowski, S.
Bardyszewski, W.
Rodak, D.
Powiązania:
https://bibliotekanauki.pl/articles/1195356.pdf
Data publikacji:
2014-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Fg
73.22.Dj
Opis:
We theoretically study the polarization-induced band inversion phenomenon in c-plane In-rich InGaN/GaN quantum wells. Our calculations performed using the k·p method with the 8×8 Rashba-Sheka-Pikus Hamiltonian for the structures with the indium content between 90% and 100% show that the reordering of the conduction and valence bands occurs for the quantum well widths below the theoretical values of critical thickness for InGaN layers pseudomorphically grown on GaN substrates.
Źródło:
Acta Physica Polonica A; 2014, 126, 5; 1154-1155
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancement of Electron Mobility and Photoconductivity in Quantum Well $In_{0.52}Al_{0.48}As//In_{0.53}Ga_{0.47}As//In_{0.52}Al_{0.48}As$ οn InP Substrate
Autorzy:
Kulbachinskii, V.
Lunin, R.
Yuzeeva, N.
Galiev, G.
Vasilievskii, I.
Klimov, E.
Powiązania:
https://bibliotekanauki.pl/articles/1399881.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.-d
73.21.Fg
73.63.Hs
Opis:
Isomorphic $In_{0.52}Al_{0.48}As//In_{0.53}Ga_{0.47}As//In_{0.52}Al_{0.48}As$ quantum well structure on InP substrate were grown by molecular beam epitaxy. We investigated the electron transport properties and mobility enhancement in the structures by changing of doping level, the width d of quantum well $In_{0.53}Ga_{0.47}As$ or by illumination using light with λ = 668 nm. Persistent photoconductivity was observed in all samples due to spatial separation of carriers. We used the Shubnikov-de Haas effect to analyze subband electron concentration and mobility. The maximal mobility was observed for quantum well width d = 16 nm.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 345-348
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polaron Effects on Nonlinear Optical Properties of a Hydrogenic Impurity in a CdTe/ZnTe Quantum Dot
Autorzy:
Azhagu Parvathi, A.
John Peter, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399298.pdf
Data publikacji:
2013-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Fg
42.65.An
71.38.-k
Opis:
Hydrogenic donor impurity binding energy is obtained in a $Zn_{x}Cd_{1-x}Te//ZnTe$ strained quantum dot taking into account the phonon confinement effect. The interaction of the electron and the phonon modes are expressed in terms of the Fröhlich interaction Hamiltonian. The binding energy is obtained for various Zn composition using the Aldrich-Bajaj effective potential. Calculations have been obtained using the Bessel function as an orthonormal basis for different confinement potentials of barrier height considering the internal electric field induced by the spontaneous and piezoelectric polarizations. Polaron induced linear and third-order nonlinear optical absorption coefficients and the changes of refractive index as a function of incident photon energy are observed. Our results coincide with the recent observations of a hydrogenic impurity binding energy in a CdTe/ZnTe quantum dot solved analytically. It is observed that the potential taking into account the effects of phonon makes the hydrogenic binding energies larger than the obtained results using a Coulomb potential screened by a static dielectric constant and the optical properties of hydrogenic impurity in a quantum dot are strongly affected by the confining potential and the quantum size. It is found that the geometry of the quantum dot, zinc concentration and the effect of phonon have a great influence on the absorption coefficient and refractive index changes of the dot. It is also observed that the magnitude of the absorption coefficients enhances with the inclusion of phonon effect.
Źródło:
Acta Physica Polonica A; 2013, 124, 4; 706-712
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Scattering of Elastic Waves in a Quasi-One-Dimensional Cavity: Theory and Experiment
Autorzy:
Báez, G.
Cobián-Suárez, M.
Martínez-Argüello, A.
Martínez-Mares, M.
Méndez-Sánchez, R.
Powiązania:
https://bibliotekanauki.pl/articles/1399047.pdf
Data publikacji:
2013-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
46.40.Cd
62.30.+d
03.65.Nk
73.21.Fg
Opis:
We study the scattering of torsional waves through a quasi-one-dimensional cavity both from the experimental and theoretical points of view. The experiment consists of an elastic rod with square cross-section. In order to form a cavity, a notch at a certain distance of one end of the rod was grooved. To absorb the waves, at the other side of the rod, a wedge, covered by an absorbing foam, was machined. In the theoretical description, the scattering matrix S of the torsional waves was obtained. The distribution of S is given by Poisson's kernel. The theoretical predictions show an excellent agreement with the experimental results. This experiment corresponds, in quantum mechanics, to the scattering by a delta potential, in one dimension, located at a certain distance from an impenetrable wall.
Źródło:
Acta Physica Polonica A; 2013, 124, 6; 1069-1073
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quasi-Particle Localization by Disorder in ν = 5/2 Fractional Quantum Hall State and Its Potential Application
Autorzy:
Goswami, P.
Powiązania:
https://bibliotekanauki.pl/articles/1418290.pdf
Data publikacji:
2012-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.21.Fg
Opis:
We consider the filling factor 5/2 fractional quantum Hall state of spin-polarized fermions in a dirty (mobility $μ_b \lt 10 m^2 V^{-1} s^{-1}$) bi-layer quantum well system.We show that the system undergoes a quantum phase transition from the effective two-component state to an effective single-component state, at fixed charge imbalance regulatory parameter $\Delta_{c}$ and constant layer separation, as the inter-layer tunneling strength $\Desta_\text{SAS}$ is increased. At finite and constant $\Delta_\text{SAS}$, a transition from the latter state to the former state is also possible upon increasing the parameter $\Delta_{c}$. We identify the order parameter to describe quantum phase transition as a pseudo-spin component and calculate this with the aid of the Matsubara propagators in the finite-temperature formalism. Our treatment is able to show that, at low temperature(< 0.1 K) and low value of charge imbalance regulatory parameter, there is a competition between the disorder and the inter-layer tunneling strength in the sample. The competition leads to the quasi-particle localization at low tunneling strength.
Źródło:
Acta Physica Polonica A; 2012, 122, 4; 741-747
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge Carrier Transport in Quantum Cascade Lasers in Strong Magnetic Field
Autorzy:
Radovanović, J.
Milanović, V.
Indjin, D.
Ikonić, Z.
Harrison, P.
Powiązania:
https://bibliotekanauki.pl/articles/1505456.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.-d
73.21.Fg
Opis:
We have developed a comprehensive rate equations based model for calculating the optical gain in the active region of a quantum cascade laser in magnetic field perpendicular to the structure layers, which takes into account all the relevant scattering channels. The model is applied to gain-optimized quantum cascade laser active region, obtained by a systematic optimization procedure based on the use of genetic algorithm, which we have previously set up for designing novel structures and improving performance of existing ones. It has proven to be very efficient in generating optimal structures which emit radiation at specified wavelengths corresponding to absorption fingerprints of particular harmful pollutants found in the atmosphere. We also illustrate another interesting prospective application of quantum cascade laser-type structures: the design of metamaterials with tunable complex permittivity, based on amplification via intersubband transitions. In this case, the role of the magnetic field is to assist the attainment of sufficient optical gain (population inversion), necessary to effectively manipulate the permittivity and fulfill the conditions for negative refraction (left-handedness).
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 99-102
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Transport in Modulation-Doped InAlAs/InGaAs/InAlAs Heterostructures in High Electric Fields
Autorzy:
Požela, K.
Požela, J.
Jucienė, V.
Vasil'evskii, I.
Galiev, G.
Klimov, E.
Sužiedėlis, A.
Žurauskienė, N.
Stankevič, V.
Keršulis, S.
Paškevič, Č.
Powiązania:
https://bibliotekanauki.pl/articles/1505525.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Ht
72.10.Di
73.21.Fg
73.63.Hs
73.40.Kp
Opis:
The following peculiarities of electron transport in $In_{0.53}Ga_{0.47}As//In_{0.52}Al_{0.48}As$ quantum wells with δ-Si-doped $In_{0.52}Al_{0.48}As$ barriers at high electric fields are discovered: (1) an enhancement of electron mobility by inserting the InAs phonon wall into the $In_{0.53}Ga_{0.47}As//In_{0.52}Al_{0.48}As$ quantum well, as well as increasing the InAs content in the modulation-doped $In_{0.8}Ga_{0.2}As//In_{0.7}Al_{0.3}As$ heterostructure; (2) a large decrease in electron mobility and a change of electron density with increasing electric field in the range of 1-4 kV/cm; (3) a magnetic field dependence of the threshold electric field for intervalley scattering of electrons; and (4) microwave current oscillations in high electric fields.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 170-172
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inter-Landau Level Scattering Processes in Magnetic Field Assisted THz Quantum Cascade Laser
Autorzy:
Radovanović, J.
Daničić, A.
Milanović, V.
Indjin, D.
Ikonic, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1503186.pdf
Data publikacji:
2011-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.10.-d
73.21.Fg
Opis:
We present a detailed analysis of GaAs/AlGaAs terahertz quantum cascade laser in the presence of an intense external magnetic field. One of the objectives in further development of THz quantum cascade laser is the realization of structures operating at higher temperatures. This is difficult to obtain as the operating photon emission energy is smaller than the longitudinal-optical phonon energy in the semiconductor material. With increased temperature, electrons in the upper radiative state gain sufficient in-plane energy to emit an longitudinal-optical phonon, which represents a non-radiative scattering and reduces the optical gain. By applying strong magnetic field, two-dimensional continuous energy subbands become split into series of discrete Landau levels, and at particular values of B it is possible to quench these non-radiative channels. Numerical simulations are performed on two-well design quantum cascade laser operating at 4.6 THz, implemented in GaAs/$Al_{0.15}Ga_{0.85}As$, and the magnetic field is perpendicular to the epitaxial layers. Strong oscillations of carrier lifetimes for the upper state of the laser transition, as a function of magnetic field are observed, which can be attributed to interface roughness scattering and longitudinal-optical phonon scattering between Landau levels.
Źródło:
Acta Physica Polonica A; 2011, 120, 2; 227-230
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement of Pulsed Current-Voltage Characteristics of AlGaN/GaN HEMTs from Room Temperature to~15~K
Autorzy:
Laurent, T.
Sharma, R.
Torres, J.
Nouvel, P.
Blin, S.
Palermo, C.
Varani, L.
Cordier, Y.
Chmielowska, M.
Faurie,, J.
Beaumont, B.
Powiązania:
https://bibliotekanauki.pl/articles/1505650.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Ey
73.21.Fg
73.40.-c
Opis:
We report measurements of the pulsed and dc current-voltage characteristics of AlGaN/GaN high-electron-mobility transistors as functions of geometry, temperature (from 300 down to 15 K), and operating conditions. An increase in the drain current with shortening of the pulse width from 1 μs to 400 ns is found to be significant at room temperature whilst this behavior is inverted or even removed at 77 and 15 K temperatures.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 196-198
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 48

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