Temperature dependence of time-resolved photoluminescence spectroscopy in InAs/GaAs quantum ring

Lin, Chien Hung; Lin, Hong-Cheng; Huang, Chun Che; Su, Shanshan; Lin, Sheng-Di; Sun, Kien-Wen; Lee, C. P.; Liu, Y. K.; Yang, Miin-Shen; Shen, Ji Lin

doi:10.1063/1.3130741

Cited by 30 publications

(18 citation statements)

References 21 publications

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“…[15] In 2 (c) the exciton energy levels are displayed for hh-excitons where the first excited levels correspond to dark excitons. By increasing the flux, starting from Φ/Φ 0 = 0 up to Φ/Φ 0 = 1/2, the dark exciton levels approach the bright-one.…”

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confidence: 99%

Aharonov-Bohm Interference in Neutral Excitons: Effects of Built-In Electric Fields

et al. 2010

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We report a comprehensive discussion of quantum interference effects due to the finite structure of excitons in quantum rings and their first experimental corroboration observed in the optical recombinations. Anomalous features that appear in the experiments are analyzed according to theoretical models that describe the modulation of the interference pattern by temperature and built-in electric fields.PACS numbers: 71.35.Ji, 73.21.La, 78.20.Ls, 78.67.Hc The nanoscale ring structures, or quantum rings (QRs), have attracted the interest of the scientific community due to their unique rotational symmetry and the possibility to verify quantum mechanical phenomena.[1, 2, 3] Among these, the study of Aharonov-Bohm (AB)-like effects has gained a significant impetus, [4,5,6] and these efforts have gone beyond the original discussion of the AB interpretation on the nature of electromagnetic potentials and their role in quantum mechanics. [7] It is reasonable to say that the study of coherent interference occurring in transport properties of nanoscopic QRs, as proposed in Ref. 7 encounters, at the moment, serious scale limitations which has encouraged the search for optical implications associated to AB-effects.These endeavors applied to nanoscopic QRs do not strictly meet the original conditions for the ABconfiguration since the carriers are confined within regions with finite values of magnetic field. However, we still consider an observed effect as of AB-type if it can be explained assuming that the magnetic field is ideally concentrated in the middle of the QRs, i. e., when such effect comes essentially from potential vector-mediated quantum interference. As also considered in Ref. 8, in stationary systems this interference is generally reflected in a boundary condition and it is not as explicit as in the famous picture of an AB scattering situation.In this work we consider AB-interference in excitonic states as proposed theoretically in Refs. 9, 10, 12. Instead of looking only at the oscillatory dependence on magnetic flux of the electron-hole (e − h) recombination energy during photo-luminescence (PL), we also consider the excitonic oscillator strength whose oscillatory behavior reflects directly the changes in the exciton wavefunction as the magnetic flux increases. A similar experimental work was reported in Ref. 6 for type-II QRs, however, here we study type-I systems where both electron and hole move in the ring so that the correlation between them is crucial to the oscillatory behavior found in the PL integrated intensity. The samples studied here were grown using a RIBER 32P solid-source molecular beam epitaxy chamber and the QRs were grown using the following procedure. A 0.5 µm GaAs buffer layer was grown on semi-insulating (100) GaAs substrates at 580• C, after oxide desorption. Then, it was followed by 2.2 ML of InAs and the formation of quantum dots (QDs) at 520• C. The dots were obtained using the Stranski-Krastanov growth mode. Cycles of 0.14 ML of InAs plus a 2 s interruption under As 2 flux were r...

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confidence: 99%

Aharonov-Bohm Interference in Neutral Excitons: Effects of Built-In Electric Fields

et al. 2010

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“…Then, the observed Arrhenius dependence of the integrated PL intensity of QD structures can be accounted by two decay processes activated at different T: the high-T decrease of PL intensity corresponds to a large activation energy consistent with the carrier escape from QD to WL or barrier levels [11]; the weak decrease of PL at intermediate T, related to activation energies of few tens of meV, has been differently attributed to resonant energy levels between different families [12], loss of carriers from the WL to the GaAs [13] or within the barrier itself [14]. These mechanisms alone, however, cannot account for the observed increase of exciton lifetime at intermediate T that, as already reported in [15,16] for self-assembled QDs and in [17,18] for quantum ring structures, may be explained by the thermal population of optically inactive QD dark states (DS).…”

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confidence: 44%

MBE growth and properties of low‐density InAs/GaAs quantum dot structures

Trevisi

Seravalli

Frigeri

et al. 2011

Cryst. Res. Technol.

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We present the results of a comprehensive study carried out on morphological, structural and optical properties of InAs/GaAs quantum dot structures grown by Molecular Beam Epitaxy. InAs quantum dots were deposited at low growth rate and high growth temperature and were capped with InGaAs upper confining layers. Owing to these particular design and growth parameters, quantum dot densities are in the order of 4-5x10 9 cm -2 with emission wavelengths ranging from 1.20 to 1.33 µm at 10 K, features that make these structures interesting for single-photon operation at telecom wavelength. High resolution structural techniques show that In content and composition profiles in the structures depend on the particular epitaxial growth conditions used to reduce the density of quantum dots. Carrier recombination dynamics in quantum dots is studied by analysing the integrated photoluminescence (PL) intensity and recombination times as functions of the temperature. Arrhenius plots of the integrated PL show two activation energies implying two decay processes. The first one is associated to thermal escape of carriers from quantum dot to wetting layer states; the second one is consistent with the thermal population of quantum dot dark states, as suggested by time resolved PL measurements.

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“…According to the research on QDs, QRs have also been well investigated because of their unique shape, symmetry and physics related to a topological singularity. The typical scheme for the fabrication of QRs is the partial capping of QDs and annealing (growth interruption) processes [1][2][3][4][5][6][7] by molecular beam epitaxy (MBE). For example, InAs QDs grown on GaAs substrates are partially capped and then annealed under As 2 atmosphere.…”

Section: Introductionmentioning

confidence: 99%