Asymmetry of charge relaxation times in quantum dots: The influence of degeneracy

Beckel, A.; Kurzmann, Annika; Geller, M.; Ludwig, Arne; Wieck, A. D.; König, Jürgen; Lorke, Axel

doi:10.1209/0295-5075/106/47002

Cited by 30 publications

(25 citation statements)

References 29 publications

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“…Bayer and Forchel [12] performed temperature dependent investigations and determined the QD's homogenous linewidth increasing only by a tiny amount compared to k B T, making QDs promising candidates for higher temperature applications. A study of the tunnelling dynamics is performed by Luyken et al [13] and a description of the differences for inand out-tunnelling rates due to degeneracy of the various electronic states is performed by Beckel et al [14].…”

Section: Introductionmentioning

confidence: 99%

Thermal shift of the resonance between an electron gas and quantum dots: what is the origin?

Brinks¹,

Wieck²,

Ludwig

2016

New J. Phys.

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The operation of quantum dots (QDs) at highest possible temperatures is desirable for many applications. Capacitance-voltage spectroscopy (C(V )-spectroscopy) measurements are an established instrument to analyse the electronic structure and energy levels of self-assembled QDs. We perform C(V ) in the dark and C(V ) under the influence of non-resonant illumination, probing exciton states up to + X 4 on InAs QDs embedded in a GaAs matrix for temperatures ranging from 2.5 to 120 K. While a small shift in the charging spectra resonance is observed for the two spin degenerate electron s-state charging voltages with increasing temperature, a huge shift is visible for the electron-hole excitonic states resonance voltages. The s 2 -peak moves to slightly higher, the s 1 -peak to slightly lower charging voltages. In contrast, the excitonic states are surprisingly charged at much lower voltages upon increasing temperature. We derive a rate-model allowing to attribute and value different contributions to these shifts. Resonant tunnelling, state degeneracy and hole generation rate in combination with the Fermi distribution function turn out to be of great importance for the observed effects. The differences in the shifting behaviour is connected to different equilibria schemes for the peaks-s-peaks arise when tunnelling-in-and out-rates become equal, while excitonic peaks occur, when electron tunnelling-in-and hole-generation rates are balanced.

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Section: Introductionmentioning

confidence: 99%

Thermal shift of the resonance between an electron gas and quantum dots: what is the origin?

Brinks¹,

Wieck²,

Ludwig

2016

New J. Phys.

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“…3 (a), to demonstrate its applicability to larger mesoscopic systems. Both settings, the singleelectron source and the multiple quantum dots, have been analyzed in recent experiments [12,13].…”

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confidence: 99%

Nonadiabatic Dynamics in Single-Electron Tunneling Devices with Time-Dependent Density-Functional Theory

2018

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We simulate the dynamics of a single-electron source, modeled as a quantum dot with on-site Coulomb interaction and tunnel coupling to an adjacent lead in time-dependent density-functional theory. Based on this system, we develop a time-nonlocal exchange-correlation potential by exploiting analogies with quantum-transport theory. The time nonlocality manifests itself in a dynamical potential step. We explicitly link the time evolution of the dynamical step to physical relaxation timescales of the electron dynamics. Finally, we discuss prospects for simulations of larger mesoscopic systems.

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“…The electron transfer can be completely described by a spinless orbital which is occupied with rate G 2 10 and emptied with rate G 01 . The factor 2 reflects the spin degeneracy [52]. Note that a separable characteristic function does not always separate in a z-dependent and z-independent factor, an example will be given in section 5.…”

Section: Single-level Quantum Dot In a Zeeman Fieldmentioning

confidence: 99%

Inverse counting statistics based on generalized factorial cumulants

Stegmann

König

2017

New J. Phys.

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We propose a procedure to reconstruct characteristic features of an unknown stochastic system from the long-time full counting statistics of some of the system's transitions that are monitored by a detector. The full counting statistics is conveniently parametrized by so-called generalized factorial cumulants. Taking only a few of them as input information is sufficient to reconstruct important features such as the lower bound of the system dimension and the full spectrum of relaxation rates. The use of generalized factorial cumulants reveals system dimensions and rates that are hidden for ordinary cumulants. We illustrate the inverse counting-statistics procedure for two model systems: a single-level quantum dot in a Zeeman field and a single-electron box subjected to sequential and Andreev tunneling. following scenario. First, only steady-state counting statistics is considered, i.e., we assume that the system has already relaxed before counting starts. This excludes studying transient behavior after a perturbation of the system. The latter would, on the one hand, offer a direct access to some relaxation rate of the system [50-54]. On the other hand, the determination of the full spectrum of relaxation rates would require the knowledge of how to perturb the system in order to probe a specific relaxation rate.Second, we concentrate on the limit of long measuring-time intervals [ ] t 0; , for which the system dynamics is dominated by the slowest relaxation rate only. Nevertheless, the procedure of inverse counting statistics yields the full spectrum of all relaxation rates, as explained below.Given a measured distribution P N (t), what are the input data for the inverse counting statistics? In [43], it was suggested to use the (long-time) cumulants of the distribution function. Here, we propose to use generalized factorial cumulants [55,56] instead. The advantage of the latter is that they depend on an arbitrarily chosen parameter s. The outcome of the inverse counting statistics (such as the number of system states or the spectrum of relaxation rates) should, however, not depend on this parameters. Therefore, the s-independence of the results defines a powerful consistency criterion. Furthermore, as we will see in section 5, there are special cases in which part of the relaxation-rate spectrum is not accessible by inverse counting statistics with ordinary cumulants but is detectable by using generalized factorial cumulants with properly chosen parameters.As another difference to[43], we allow for a more general system-detector coupling by introducing the counting power m. In[43], the detector is assumed to be sensitive to only a single transition between two specific states increasing the detector counter just by one, the counting power is m=1. If this transition increases the detector counter by k, the counting power is m=k. If several transitions are counted by the detector, the counting power can be even larger. We allow for detectors counting arbitrarily many transitions between arbitrarily many sta...

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Asymmetry of charge relaxation times in quantum dots: The influence of degeneracy

Cited by 30 publications

References 29 publications

Thermal shift of the resonance between an electron gas and quantum dots: what is the origin?

Thermal shift of the resonance between an electron gas and quantum dots: what is the origin?

Nonadiabatic Dynamics in Single-Electron Tunneling Devices with Time-Dependent Density-Functional Theory

Inverse counting statistics based on generalized factorial cumulants

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