Temat: 73.21.La - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Exact diagonalization approach for atomistic calculation of piezoelectric effects in semiconductor quantum dots
Autorzy:: Świderski, M.
Zieliński, M.
Tematy:: 73.21.La; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1075363.pdf Link otwiera się w nowym oknie
Opis:: We present an exact diagonalization approach for atomistic calculation of excitonic properties of semiconductor nanostructures under piezoelectric field. The method allows for efficient treatment of both single particle and many-body states at a small computational cost and results in a very good agreement with the full diagonalization treatment. We illustrate our approach by analyzing the effect of a piezoelectric field on a spectra of a self-assembled InAs/GaAs lens-shaped quantum dot. We study the influence of linear and quadratic piezoelectric terms on the quantum dot electronic structure and importantly we found that the non-linear, density functional based theory of piezoelectricity produces results very similar to those obtained by a well-established linear approach utilizing empirical parameters.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Influence of Magnetic Field on Dark States in Transport through Triple Quantum Dots
Autorzy:: Wrześniewski, K.
Weymann, I.
Tematy:: 73.23.-b
73.21.La; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1032454.pdf Link otwiera się w nowym oknie
Opis:: We theoretically study the electronic transport through a triple quantum dot system in triangular geometry weakly coupled to external metallic leads. By means of the real-time diagrammatic technique, the current and Fano factor are calculated in the lowest order of perturbation theory. The device parameters are tuned to such transport regime, in which coherent population trapping of electrons in quantum dots due to the formation of dark states occurs. The presence of such states greatly influences transport properties leading to a strong current blockade and enhanced, super-Poissonian shot noise. We consider both one- and two-electron dark states and examine the influence of magnetic field on coherent trapping in aforementioned states. When the system is in one-electron dark state, we observe a small shift of the blockade's region, whereas in the case of two-electron dark state, we show that strong magnetic field can lift the current blockade completely.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Effect of retrapping on thermoluminescence peak intensities of small amorphous silicon quantum dots
Autorzy:: Debelo, N.
Dejene, F.
Mal'nev, V.
Senbeta, T.
Mesfin, B.
Roro, K.
Tematy:: 73.21.La
73.63.Kv; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1070477.pdf Link otwiera się w nowym oknie
Opis:: The effect of retrapping on thermoluminescence intensity peak corresponding to each trap of small amorphous silicon quantum dots in three traps - one recombination center model is investigated. For first order kinetics, where there is no effect of retrapping, the thermoluminescence intensity clearly depends on the level of the trap beneath the edge of the conduction band. This energy difference between the edge of the conduction band and the level of the trap is called trap depth (activation energy). The shallowest trap gives the highest thermoluminescence intensity peak for first order kinetics. However, it was clearly observed that for second order and a case beyond second order kinetics, the thermoluminescence intensity peak corresponding to each trap does not depend on the trap depth. In this case, the retrapping probability coefficients are taken into account and most electrons which are detrapped from the shallow trap(s) will be retrapped to the deeper trap(s) resulting in fewer electrons taking part in the recombination process. This significantly reduces the thermoluminescence intensity peaks of the shallower trap(s). It was observed that the deepest trap, with very high concentration of electrons due to the retrapping phenomenon, gives the highest thermoluminescence intensity. In addition, the variation of concentration of electrons in each trap and the intensity of the thermoluminescence are presented. Though we considered the model of three traps and one recombination center, this phenomenon is true for any multiple traps.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Energy Band and Absorption Coefficient of Quantum Dots in a Well Structure
Autorzy:: Zhang, P.
Lu, X.
Zhang, C.
Yao, J.
Tematy:: 73.21.La
73.63.Kv; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1419887.pdf Link otwiera się w nowym oknie
Opis:: Building on the effective-mass envelope function theory, this paper focuses on the study of the energy band and the absorption coefficient of $InAs//In_{x}Ga_{1 - x}As$ quantum dots in a well (DWELL) structure. In contrast to $InAs//In_{0.15}Ga_{0.85}As$ quantum DWELL, the $InAs//In_{0.2}Ga_{0.8}As$ quantum DWELL has lower ground states. With the thickness of $In_{0.15}Ga_{0.85}As$ layer changing from 7 nm to 9 nm and $In_{0.2}Ga_{0.8}As$ layer changing from 9 nm to 12 nm, the calculation shows that their absorption coefficient spectra takes a red shift in the long-wave infrared and far-infrared ranges, respectively. Moreover, when the thickness of the $In_{x}Ga_{1 - x}As$ layer is defined as 9 nm, the absorption coefficient spectra of $InAs//In_{0.2}Ga_{0.8}As$ DWELL shows a obvious red shift comparing with that of $InAs//In_{0.15}Ga_{0.85}As$ DWELL.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Si Multidot FETs for Single-Electron Transfer and Single-Photon Detection
Autorzy:: Tabe, M.
Nuryadi, R.
Moraru, D.
Burhanudin, Z.
Yokoi, K.
Ikeda, H.
Tematy:: 73.21.La
73.23.Hk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1813190.pdf Link otwiera się w nowym oknie
Opis:: Recently, there have been increasing demands for controlling individual electrons, photons, and dopants in developing nm scale Si devices. Our most recent results on Si single-electron nano-devices will be presented. We have demonstrated single-electron transfer in random-tunnel-junctions by a cycle of ac gate bias, detection of photons and detection of individual acceptor ions by Si single-hole transistor.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 6.

Tytuł:: Electron and Hole States in Closed Spherical Quantum Dot with Linearly Graded Composition
Autorzy:: Kostić, R.
Stojanović, D.
Tematy:: 73.22.Dj
73.21.La; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1808044.pdf Link otwiera się w nowym oknie
Opis:: The theoretical investigation of the electron and hole spectra in a quantum dot with a linearly graded composition within the effective mass approximation is presented. The particular example is β-HgS surrounded by CdS. β-HgS core of radius $r_C$ is surrounded by concentric spherical layers each of $Hg_{1-x}Cd_{x}S$ composition (x is function of r) and finally, form radius $r_S$ by CdS. The existence of these intermediate layers, as model of graded composition, influences rapidly electron and hole spectra.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 7.

Tytuł:: Spin-Dependent Coupling of Charged Quantum Dot Excitons with Continuum States
Autorzy:: Urbaszek, B.
Warburton, R. J.
Karrai, K.
Schulhauser, C.
Högele, A.
McGhee, E. J.
Govorov, A. O.
Gerardot, B. D.
Marie, X.
Amand, T.
Petroff, P. M.
Tematy:: 73.21.La
78.67.Hc; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2038350.pdf Link otwiera się w nowym oknie
Opis:: Magnetic field and temperature dependent photoluminescence studies on neutral and charged excitons in individual InAs quantum dots allow us to uncover different mechanisms by which the discrete quantum dot states are coupled to delocalized continuum states in a quantum well (the wetting layer). The behaviour of the neutral and singly charged excitons can be explained taking only discrete quantum dot states into account. For doubly and triply charged excitons we have to consider spin dependent coherent and incoherent interactions between discrete quantum dot states and delocalized wetting layer states.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 8.

Tytuł:: Binding Energy of the Hydrogenic Impurity in CdTe/ZnTe Spherical Quantum Dot
Autorzy:: Stojanović, D.
Kostić, R.
Tematy:: 73.21.La
71.55.-i; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1503269.pdf Link otwiera się w nowym oknie
Opis:: Binding energy of a hydrogenic impurity located at the center of the CdTe/ZnTe spherical quantum dot has been calculated under the effective mass approximation by solving Schrödinger equation analytically. Eigen energies are expressed in terms of the Whittaker function and Coulomb wave function. The results show that impurity binding energy strongly depends on QD size if it is around one effective Bohr radius.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 9.

Tytuł:: Numerical Rate Equation Approach to Picosecond Charge State Dynamics in CdTe/ZnTe Quantum Dots
Autorzy:: Koperski, M.
Kazimierczuk, T.
Goryca, M.
Wojnar, P.
Golnik, A.
Kossacki, P.
Gaj, J.
Tematy:: 78.55.Et
73.21.La; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1791339.pdf Link otwiera się w nowym oknie
Opis:: The rate equation is used for description of photoluminescence dynamics after pulsed excitation of various states of quantum dots. The picosecond dynamics of averaged charge state of quantum dot is described. We compare our simulations with the experiment and come up with the conclusion that probability of carrier capture weakly depends on quantum dot charge state and that electrons and holes are captured non-synchronously.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 10.

Tytuł:: The calculation for strain distributions and electronic structure of InAs/GaAs quantum dots based on the eight-band k·p theory
Autorzy:: Shu, Changgan
Liu, Yumin
Tematy:: 73.21.La
73.63.Kv; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1070532.pdf Link otwiera się w nowym oknie
Opis:: In order to analyze the strain distribution of InAs/GaAs quantum dot in a pyramidal geometry, the traditional calculation method is based on the single band envelope approximation with the modified band edge from the eight band k·p theory. In this paper, we use the eight band k·p Hamiltonian to calculate, and the piezoelectric effects and the electronic structure are also discussed subsequently. To this end, some necessarily derived formulae in calculations about using the finite element calculation software COMSOL are presented in this paper. The results show the details about strain distributions, piezoelectric effects and electronic structure of an InAs/GaAs pyramidal quantum dot, verify the feasibility and efficiency of the calculation method.
Dostawca treści:: Biblioteka Nauki

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