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Wyszukujesz frazę "Quantum dot" wg kryterium: Temat


Wyświetlanie 1-14 z 14
Tytuł:
Spatio-Temporal Dynamics of Carrier Capture Processes: Simulation of Optical Signals
Autorzy:
Lengers, F.
Rosati, R.
Kuhn, T.
Reiter, D.
Powiązania:
https://bibliotekanauki.pl/articles/1033096.pdf
Data publikacji:
2017-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
quantum dot
carrier capture
optical signals
Opis:
We perform simulations of time-resolved optical experiments of carrier-capture processes in a quantum wire-dot system. Scattering of charge carriers with optical phonons of the quantum wire can result in transitions from the continuum states of the quantum wire to discrete states of the quantum dot. We treat the scattering of carriers with optical phonons within a Lindblad single-particle approach. By considering the coupling of carriers to a light field we are able to simulate pump-probe experiments which are shown to be capable of measuring the captured populations. We further discuss the influence of the Coulomb interaction on the obtained spectra.
Źródło:
Acta Physica Polonica A; 2017, 132, 2; 372-375
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical bistability in double quantum dot molecule with inter-dot tunnelling
Autorzy:
Yu, Chunchao
Sun, Lihui
Zhang, Huafeng
Chen, Fang
Powiązania:
https://bibliotekanauki.pl/articles/174307.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optical bistability
quantum dot molecule
tunneling
Opis:
We have theoretically studied the optical bistability behaviors under an external electric field and a coupling laser field in double quantum dot molecule system with π-type four energy levels. It can be adjusted by the system parameters such as the electronic cooperation parameter, the tunneling strength, the coupling laser field, the probe and coupling laser detuning. These results may be useful in the experiment and provide new types of all-optical switching.
Źródło:
Optica Applicata; 2019, 49, 2; 293-301
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A numerical solution of the Poisson-Schrodinger problem for a vertical gated quantum dot
Autorzy:
Lis, K.
Bednarek, S.
Adamowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1964204.pdf
Data publikacji:
2004
Wydawca:
Politechnika Gdańska
Tematy:
semiconductor quantum dot
quantum dots
Poisson-Schrodinger problem
Opis:
We present a numerical solution of the Poisson-Schrodinger problem for a semiconductor nanostructure containing a single quantum dot. The main outcome of our work is the lateral confinement potential, which determines the electronic properties of the nanodevice. We study the real nanodevice with cylindrical symmetry, which allows us to solve the three-dimensional problem on a two-dimensional mesh. We discuss the self-consistency of the solution with respect to the distribution of ionized donors inside the nanodevice.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2004, 8, 4; 603-611
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Output-input properties of incident light on a defect dielectric slab with quantum dot nanostructure
Autorzy:
Jafarzadeh, Hossein
Powiązania:
https://bibliotekanauki.pl/articles/174095.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
quantum dot nanostructure
optical bistability
optical multistability
Opis:
We demonstrate output-input properties of incident light in a defect slab doped by three-level quantum dot nanostructure via quantum coherence and Fano-interference phenomena. Here, we will show that the output-input properties of the system can be adjusted by the Fano-interference strength, amplitude and the relative phase of the driving fields, respectively. Also, we consider the thickness effect of defect medium on controlling the output-input behaviors of probe light. Moreover, we realize that it is possible to switch between optical bistability and optical multistability by optimizing the conditions which are more practical in all-optical switching based nanoscale devices.
Źródło:
Optica Applicata; 2019, 49, 1; 101-113
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman spectroscopy of CdTe/ZnTe quantum dot structures
Autorzy:
Zielony, E
Placzek-Popko, E
Kamyczek, P
Henrykowski, A
Karczewski, G
Powiązania:
https://bibliotekanauki.pl/articles/174898.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Raman spectroscopy
CdTe
ZnTe
quantum dot structures
Opis:
Semiconductor low-dimensional structures of CdTe quantum dots (QDs) embedded in ZnTe matrix have been investigated by micro-Raman spectroscopy. A reference ZnTe sample (without dots) was also studied for comparison. Both samples were grown by a molecular beam epitaxy technique on the p-type GaAs substrate. The Raman measurements have been performed at room temperature. The samples were excited by an Ar2+ laser of 514.5 nm wavelength. The Raman spectra have been recorded for different acquisition parameters of the measurement. For the reference and QD sample localized longitudinal (LO) phonons of 210 cm–1 wavenumber associated with the ZnTe layer are observed. In the case of QD sample another broadband corresponding to the LO CdTe phonon related to the QD-layer appears at a wavenumber of 160 cm–1. Such behaviour does not exhibit the Raman spectra of the reference sample. Thus the Raman measurements confirm the presence of CdTe layer of quantum dots in the investigated material. Additionally, Raman spectra for both samples exhibit tellurium-related peaks at wavenumbers around 120 cm–1 and 140 cm–1, significantly increasing with laser time exposure. It is shown that the peaks are associated with the formation of Te aggregates on the ZnTe surface due to the laser damage in the ZnTe layer.
Źródło:
Optica Applicata; 2013, 43, 1; 181-185
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Double tunneling induced transparency in the asymmetry quantum dot molecules
Autorzy:
Yu, C.
Huang, H.
Zhang, L.
Xu, D.
Powiązania:
https://bibliotekanauki.pl/articles/173599.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
quantum dot molecule
slow light
tunneling induced transparency
Opis:
Using the density matrix theory, we have studied the double tunneling induced transparency slow light in the double asymmetry quantum dot molecules. With applied electric field, double tunneling induced transparency occur in the same time. Four absorption peaks are found near the resonance energy level in the absorption spectrum and the absorption peak can be tuned by the applied electric field. The velocity and bandwidth of the multiple-windows slow light can also be controlled by the applied electric field. In our model, with Te =0.1meV, we can get about 0.001c and 20GHz bandwidth in each transparency window. Such a property may be applied in all optical buffers, optical switching and filter.
Źródło:
Optica Applicata; 2016, 46, 3; 473-481
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamical and Steady State Processes of Probe Absorption-Dispersion in a Four-Level Quantum Dot Nanostructure
Autorzy:
Asadi Amirabadi, E.
Jamshidnejad, M.
Miraboutalebi, S.
Asadpour, S.
Powiązania:
https://bibliotekanauki.pl/articles/1032323.pdf
Data publikacji:
2017-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
quantum dot nanostructure
absorption
dispersion
optical transient processes
Opis:
In this paper, we investigated the transient electron population and the transient behaviour of the dispersion, absorption and refractive property of weak probe light in a four-level InGaN/GaN quantum dot nanostructure. In order to achieve the wave functions and their corresponding energy levels of the mentioned quantum dot nanostructure, the Schrödinger and Poisson equations is solved selfconsistently for carriers (here electron) in quantum dot. Our findings show that the properties of transient processes can be dramatically affected by parameters such as intensity, detuning and relative phase of applied fields. Our proposed scheme provides a realistic model for transient control of refraction index properties in a quantum dot nanostructure. These results may have potential applications in high speed optical switch for quantum information technologies.
Źródło:
Acta Physica Polonica A; 2017, 131, 6; 1460-1465
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computer simulation of the working cycle of a quantum controlled-NOT gate with two coupled quantum dots
Autorzy:
Moskal, S.
Bednarek, S.
Adamowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1964205.pdf
Data publikacji:
2004
Wydawca:
Politechnika Gdańska
Tematy:
semiconductor quantum dot
quantum date operation
controlled-NOT (CNOT) gate
Opis:
We discuss a possible realization of a quantum controlled-NOT gate with the use of two coupled quantum dots. Transitions between quantum states of a computational basis are driven by the microwave π-pulse. The parameters of the proposed nanodevice have been optimized in order to make the operation cycle of the gate as short as possible. Numerical solutions of the time-dependent Schrodinger equation allow us to simulate transitions between the quantum states which correspond to the subsequent stages of the gate's operation. The performed time-dependent simulations are a test of realizability of the quantum controlled-NOT gate in the nanodevice.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2004, 8, 4; 591-602
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Strain distributions in group IV and III-V semiconductor quantum dots
Autorzy:
Wijewardena Gamalath, K. A. I. L.
Fernando, M.A.I.P.
Powiązania:
https://bibliotekanauki.pl/articles/411953.pdf
Data publikacji:
2013
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
quantum dot
strain distribution
hydrostatic strain
biaxial strain
Opis:
A theoretical model was developed using GreenˇŚs function with an anisotropic elastic tensor to study the strain distribution in and around three dimensional semiconductor pyramidal quantum dots formed from group IV and III-V material systems namely, Ge on Si, InAs on GaAs and InP on AlP. A larger positive strain in normal direction which tends to zero beyond 6nm was observed for all three types while the strains parallel to the substrate were negative. For all the three types of quantum dots hydrostatic strain and biaxial strain along x and z directions were not linear but described a curve with a maximum positive value near the base of the quantum dot. The hydrostatic strain in x-direction is mostly confined within the quantum dot and practically goes to zero outside the edges of the quantum dot. For all the three types, the maximum hydrostatic and biaxial strains occur in x-direction around �{1nm and around 2nm in z-direction. The negative strain in x-direction although realtively weak penetrate more deeper to the substrate than hydrostatic strain.The group IV substrate gave larger hydrostatic and biaxial strains than the group III-V semiconductor combinations and InAs /GaAs was the most stable. The results indicated that the movements of atoms due to the lattice mismatch were strong for group III-V.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2013, 2; 36-48
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Goos–Hänchen shift via refractive index control of four-level quantum dot nanostructure
Autorzy:
Jafarzadeh, H.
Powiązania:
https://bibliotekanauki.pl/articles/173281.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
quantum dot nanostructure
Goos–Hänchen shift
negative refractive index
Opis:
In this paper, we will discuss the Goos–Hänchen shifts properties of reflected and transmitted light beams from the cavity with four-level InGaN/GaN quantum dots nanostructure. We find that the Goos–Hänchen shifts properties of reflected and transmitted light beams can be controlled via adjusting the refractive index of four-level quantum dot nanostructure. Here, we show that by tunable infrared laser field the negative refraction index can be possible at certain values of probe frequency. Therefore, the large Goos–Hänchen shifts for reflected and transmitted light beams are possible for negative refractive index condition.
Źródło:
Optica Applicata; 2018, 48, 3; 499-513
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Power-induced lasing state switching and bistability in a two-state quantum dot laser subject to optical injection
Autorzy:
Jiang, Zaifu
Wu, Zhengmao
Jayaprasath, Elumalai
Yang, Wenyan
Hu, Chunxia
Cui, Bing
Xia, Guangqiong
Powiązania:
https://bibliotekanauki.pl/articles/173329.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
two-state quantum dot laser
lasing state switching
bistability
optical injection
Opis:
We theoretically investigate power-induced lasing state switching and bistability in a two-state quantum dot laser subject to optical injection. The simulated results show that, for a free-running two-state quantum dot laser operating at the ground state under low current, a power-induced lasing state switching between the ground state and the excited state can be achieved through introducing optical injection with a frequency (winj) close to the lasing frequency of excited state (wES). The injection power required for the state switching depends on the scanning route of injection power, i.e. there may exist state bistability for the injection power within a certain region. For forward scanning injection power, with the increase of frequency detuning (ΔΩ = winj – wES), the injection power required for the state switching shows a decreasing trend accompanied by slight fluctuations. However, for backward scanning injection power, the injection power required for the state switching exhibits obvious fluctuations with the increase of ΔΩ. The width of the hysteresis loop fluctuates with ΔΩ, and the fluctuation amplitude is increased with the increase of the injection current. Additionally, the influences of the inhomogeneous broadening factor and the electron escape rate on the bistability performances are analyzed.
Źródło:
Optica Applicata; 2020, 50, 2; 257-269
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An obtaining of nanoheteroepitaxial structures with quantum dots for high effective photovoltaic devices, investigation of their properties
Poluchenie nanogeteroehpitaksialnykh struktur s kvantovymi tochkami dlja vysokoehffektivnykh solnechnykh ehlementov, issledovanie ikh svojjstv
Autorzy:
Maronchuk, I.
Bykovsky, S.
Bondarec, S.
Velchenko, A.
Powiązania:
https://bibliotekanauki.pl/articles/792288.pdf
Data publikacji:
2014
Wydawca:
Komisja Motoryzacji i Energetyki Rolnictwa
Tematy:
nanoheteroepitaxial structure
quantum dot
liquid phase
substrate
photovoltaic device
investigation
property
semiconductor compound
Źródło:
Teka Komisji Motoryzacji i Energetyki Rolnictwa; 2014, 14, 1
1641-7739
Pojawia się w:
Teka Komisji Motoryzacji i Energetyki Rolnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of performance limits of the HOT HgCdTe photodiodes with colloidal quantum dot infrared detectors
Autorzy:
Rogalski, A.
Kopytko, M.
Martyniuk, P.
Hu, W.
Powiązania:
https://bibliotekanauki.pl/articles/201444.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
colloidal quantum dot infrared photodetectors
HOT infrared detectors
HgCdTe photodiodes
p-i-n depleted photodiodes
BLIP performance
Opis:
In the past decade, there has been significant progress in development of the colloidal quantum dot (CQD) photodetectors. The QCD’s potential advantages include: cheap and easy fabrications, size-tuneable across wide infrared spectral region, and direct coating on silicon electronics for imaging, which potentially reduces array cost and offers new modifications like flexible infrared detectors. The performance of CQD high operating temperature (HOT) photodetectors is lower in comparison with detectors traditionally available on the global market (InGaAs, HgCdTe and type-II superlattices). In several papers their performance is compared with the semiempirical rule, “Rule 07” (specified in 2007) for P-on-n HgCdTe photodiodes. However, at present stage of technology, the fully-depleted background limited HgCdTe photodiodes can achieve the level of room-temperature dark current considerably lower than predicted by Rule 07. In this paper, the performance of HOT CQD photodetectors is compared with that predicted for depleted P-i-N HgCdTe photodiodes. Theoretical estimations are collated with experimental data for both HgCdTe photodiodes and CQD detectors. The presented estimates provide further encouragement for achieving low-cost and high performance MWIR and LWIR HgCdTe focal plane arrays operating in HOT conditions.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 4; 845-855
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic structures of CdSe quantum dots embedded in ZnSe
Autorzy:
Jayawardhana, M. R. P. I.
Wijewardena Gamalath, K. A. I. L.
Powiązania:
https://bibliotekanauki.pl/articles/1178287.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
LCAO method
Quantum dot
Sparse matrices
adjacency matrix
folded spectrum method
optical matrix elements
strain effects
valence band offset
Opis:
The electronic structures and optical matrix elements of CdSe semiconductor quantum dots of near cubical, hemispherical and cylindrical shape embedded in ZnSe were calculated. Bulk Hamiltonian matrices were obtained using the empirical tight binding method including spin-orbital coupling and relativistic effects. All quantum dots were simulated in reciprocal space and the number of atoms in each quantum dot was kept nearly equal for the comparison purpose. An adjacency matrix was produced which indicates the adjacencies of unit cells and the bulk Hamiltonian was included for each adjacency point in order to obtain the quantum dot Hamiltonians. The strain effects, valence band offset and spin orbital coupling were included in the calculations. The quantum dot Hamiltonian was solved to obtain the highest and lowest eigenvalues from which the electronic structure was obtained. Then eigenvalues near integers ranging from the lowest eigenvalue to highest eigenvalue was generated for the point.
Źródło:
World Scientific News; 2017, 86, 3; 205-225
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-14 z 14

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