共查询到20条相似文献,搜索用时 750 毫秒
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胶体半导体量子点具有宽带吸收、窄带发射、发光量子产率高、发射波长连续可调等优点,是制备发光二极管、太阳能电池、探测器、激光器等光电器件的优质材料.单量子点光谱能够消除系综平均效应,可以在单粒子水平上获取量子点材料的结构和动力学信息及与其他材料间的电荷、能量转移动力学等.相关研究结果能够指引量子点材料的设计和为量子点的相关应用提供机理基础.另外基于单量子点可以开展纳米尺度上光与物质的相互作用研究,制备单光子源和纠缠光子源等.本文综述了单量子点光谱与激子动力学近期的相关研究进展,主要包括单量子点的光致发光闪烁特性和调控方式、单激子和多激子动力学研究及双激子辐射特性的调控等.最后简要地讨论了单量子点光谱未来可能的发展趋势. 相似文献
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测定了亚单层InGaAs/GaAs量子点-量子阱异质结构在5K下的时间分辨光致发光谱.亚单层量 子点的辐射寿命在500 ps 至 800 ps之间,随量子点尺寸的增大而增大,与量子点中激子的 较小的横向限制能以及激子从小量子点向大量子点的隧穿转移有关.光致发光上升时间强烈 依赖于激发强度密度.在弱激发强度密度下,上升时间为 35 ps,纵光学声子发射为主要的 载流子俘获机理.在强激发强度密度下,上升时间随激发强度密度的增加而减小,俄歇过程 为主要的载流子俘获机理.该结果对理解亚单层量子点器件的工作特性非常有用.
关键词:
亚单层
量子点-量子阱
时间分辨光致发光谱 相似文献
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The spontaneous emission (SE) of quantum dot (QD) excitons into surface plasmons in a cylindrical nanowire is investigated theoretically. Maxwell's equations with appropriate boundary conditions are solved numerically to obtain the dispersion relations of surface plasmons. The SE rate of QD excitons is found to be greatly enhanced at certain values of the exciton bandgap. Application in generation of remote entangled states via superradiance is also pointed out and may be observable with current technology. 相似文献
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Stievater TH Li X Steel DG Gammon D Katzer DS Park D Piermarocchi C Sham LJ 《Physical review letters》2001,87(13):133603
Transient nonlinear optical spectroscopy, performed on excitons confined to single GaAs quantum dots, shows oscillations that are analogous to Rabi oscillations in two-level atomic systems. This demonstration corresponds to a one-qubit rotation in a single quantum dot which is important for proposals using quantum dot excitons for quantum computing. The dipole moment inferred from the data is consistent with that directly obtained from linear absorption studies. The measurement extends the artificial atom model of quantum dot excitonic transitions into the strong-field limit, and makes possible full coherent optical control of the quantum state of single excitons using optical pi pulses. 相似文献
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C. Schulhauser R. J. Warburton A. Hgele A. O. Govorov K. Karrai J. M. Garcia B. D. Gerardot P. M. Petroff 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):184
We report on optical spectroscopy of self-assembled InAs quantum dots in a magnetic field. We describe how we measure the emission characteristics of a single quantum dot (QD) in high magnetic fields at low temperature using a miniature, fiber-based confocal microscope. Example results are presented on a QD whose charge can be controlled using a field-effect device. For the uncharged, singly and doubly charged excitons we find a diamagnetism and the spin Zeeman effect. In contrast, for the triply-charged exciton we find a fundamentally different behavior. Anti-crossings in magnetic field imply that confined states of the QD are hybridized with Landau-like levels associated with the two-dimensional continuum. 相似文献
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S. Alon-Braitbart E. Poem L. Fradkin N. Akopian S. Vilan E. Lifshitz E. Ehrenfreund D. Gershoni B.D. Gerardot A. Badolato P.M. Petroff 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):127
We fully characterize the fine spectral structure of neutral and negatively charged single microcavity quantum dot excitons, using polarization-sensitive magneto-photoluminescence spectroscopy. We show that the microcavity allows the simultaneous detection of both the bright and dark excitons using Faraday configuration. Thus, we were able to fully determine the fine structure and the g-factors of the neutral and negatively charged single exciton states within the same single quantum dot. Our measurements are in excellent agreement with novel, many carrier model calculations, which take into account Coulomb and exchange interactions among all the confined e–h pair states. 相似文献
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Laurent S Eble B Krebs O Lemaître A Urbaszek B Marie X Amand T Voisin P 《Physical review letters》2005,94(14):147401
We report on optical orientation of singly charged excitons (trions) in charge-tunable self-assembled InAs/GaAs quantum dots. When the charge varies from 0 to -2, the trion photoluminescence of a single quantum dot shows up and under quasiresonant excitation gets progressively polarized from zero to approximately 100%. This behavior is interpreted as the electric control of the trion thermalization process, which subsequently acts on the hole-spin relaxation driven in nanosecond time scale by the anisotropic electron-hole exchange. This is supported by the excitation spectroscopy and time-resolved measurements of a quantum dot ensemble. 相似文献
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Reitzenstein S Löffler A Hofmann C Kubanek A Kamp M Reithmaier JP Forchel A Kulakovskii VD Keldysh LV Ponomarev IV Reinecke TL 《Optics letters》2006,31(11):1738-1740
We report a new type of coupling between quantum dot excitons mediated by the strong single-photon field in a high-finesse micropillar cavity. Coherent exciton coupling is observed for two dots with energy differences of the order of the exciton-photon coupling. The coherent coupling mode is characterized by an anticrossing with a particularly large line splitting of 250 microeV. Because of the different dispersion relations with temperature, the simultaneous photonic coupling of quantum dot excitons can be easily distinguished from cases of sequential strong coupling of two quantum dots. 相似文献
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Ph. Lelong K. Suzuki G. Bastard H. Sakaki Y. Arakawa 《Physica E: Low-dimensional Systems and Nanostructures》2000,7(3-4)
We report on calculation of binding energies of excitons as well as positively and negatively charged excitons and biexcitons in type-II quantum dots. The shape of the GaSb/GaAs quantum dot is assumed lens-like and the energies are calculated within the Hartree–Fock approximation. A large enhancement of the binding energies has been estimated in comparison with the type-I quantum dots (InAs/GaAs) which is in good agreement with the recent experimental findings. 相似文献
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We present a decay formula for photoluminescence of a single quantum dot. We apply the formula to time-resolved photoluminescence
(PL) measurements for a single InAs/GaAs quantum dot. The formula works very well for the PL decays of excitons and biexcitons
in the system. The physical basis of the formula originates from the temporal dispersion of lifetimes.
PACS 78.67.Hc; 78.47.+p; 78.55.Cr; 71.35.-y 相似文献
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Gerhard Ortner I. Yugova A. Larionov G. Baldassarri H.v.H. M. Bayer P. Hawrylak S. Fafard Z. Wasilewski 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):281
During the recent years semiconductor nanostructures have attracted considerable interest with respect to potential applications in quantum information processing. In particular, quantum dot molecules have been suggested to provide the building block of a quantum computer: forming quantum gates due to coherent coupling of two dots. The characteristic dependence of the splitting of ‘bonding’ and ‘anti-bonding’ states suggests coherent coupling of two InAs/GaAs quantum dots. Anti-crossings in the fine structure of excitons due to mixing of optically bright and dark states have been observed in Faraday configuration. In Voigt configuration the diamagnetic shift of the quantum dot molecule is enhanced compared to a single quantum dot. These findings altogether demonstrate the coherent coupling of exciton states in quantum dot molecules. 相似文献
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《Superlattices and Microstructures》1999,25(1-2):119-125
Employing two different growth methods: standard molecular beam epitaxy (MBE) and low-temperature atomic layer epitaxy (ALE) with subsequent annealing, we have obtained high-quality quantum dot structures consisting of CdSe embedded in ZnSe. Single dot emission lines are observed in micro-luminescence. The samples have been investigated by further optical methods including time-resolved photoluminescence under resonant excitation at 4.2 K. Distinct properties of systems with three-dimensional confinement are observed such as the suppression of the interaction between isolated quantum dots (QDs). In standard quantum wells tunneling/hopping processes generally lead to a pronounced red shift of the luminescence over time due to a lateral localization of excitons in potential fluctuations. A much less pronounced red shift is observed for the QDs reflecting only the different lifetimes of single dots and higher excited states. The red shift completely vanishes under resonant excitation that selectively excites only a few QDs of the ensemble in the layer. Typical behaviour is also observed from the halfwidth of the quantum dot emission. 相似文献