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Volumn 71, Issue 12, 2005, Pages

Fine structure in the excitonic emission of InAs/GaAs quantum dot molecules

Author keywords

[No Author keywords available]

Indexed keywords

ARSENIC DERIVATIVE; GALLIUM; INDIUM;

EID: 20144374572     PISSN: 10980121     EISSN: 1550235X     Source Type: Journal    
DOI: 10.1103/PhysRevB.71.125335     Document Type: Article
Times cited : (47)

References (77)
  • 21
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    • Overviews of single dot spectroscopy are given, for example, in A. Zrenner, J. Chem. Phys. 112, 7790 (2000);
    • (2000) J. Chem. Phys. , vol.112 , pp. 7790
    • Zrenner, A.1
  • 27
    • 0035887479 scopus 로고    scopus 로고
    • Phys. Rev. B 64, 153302 (2002);
    • (2002) Phys. Rev. B , vol.64 , pp. 153302
  • 28
    • 4243650828 scopus 로고    scopus 로고
    • Phys. Rev. Lett. 88, 167401 (2002);
    • (2002) Phys. Rev. Lett. , vol.88 , pp. 167401
  • 29
    • 0038219641 scopus 로고    scopus 로고
    • Phys. Rev. B 67, 125308 (2003).
    • (2003) Phys. Rev. B , vol.67 , pp. 125308
  • 39
    • 20144382161 scopus 로고    scopus 로고
    • note
    • Since the relaxation from the p-shell into the s-shell molecule states is fast, one observes for the p shell the typical state filling effects as for the quantum dot reference. For the 5 nm barrier sample in Fig. 2, for example, first the "bonding" p-shell state becomes occupied with increasing excitation, and only after its filling also the "antibonding" p-shell state becomes populated.
  • 40
    • 20144367388 scopus 로고    scopus 로고
    • note
    • The precise linewidth is hard to determine since often a few fine structure lines with small energy splittings in between contribute to the emission, as in case of the ground state emission (see discussion in text). Within this multiplet, no spectral filtering through polarization selection is possible, since the involved states in most cases are not pure angular momentum states.
  • 41
    • 20144380748 scopus 로고    scopus 로고
    • note
    • The temperature increase leads to a low-energy shift of the quantum dot molecule emission due to the related band gap reduction.
  • 42
    • 20144366635 scopus 로고    scopus 로고
    • note
    • We note that in Ref. 14 we had erroneously interpreted the increase of intensity from the higher-lying molecule exciton state upon increasing temperature as caused by thermal excitation. This was based on the absence of significant emission from multiexciton complexes while increasing simultaneously the excitation power. The origin of the emission intensity dependencies on temperature and excitation is not yet fully understood. A simple estimate shows that the change of occupation probabilities by a temperature increase from 10 to 50 K is not sufficient to explain the changes of the ratio of emission intensity from "bonding" and "antibonding" states in the spectra.
  • 43
    • 20144367898 scopus 로고    scopus 로고
    • note
    • We note that for a given barrier width there is also a weak correlation between the absolute energies of "bonding" and "antibonding" states and the energy splitting between them: the higher the center of gravity of the line energies is, the larger is the tunnel splitting. This correlation can be easily understood, since the tunnel matrix element increases (leading to a larger tunnel splitting) for smaller energy separation from the top of the barrier, i.e., the barrier height (assuming a constant tunnel barrier height for simplicity).
  • 48
    • 20144364039 scopus 로고    scopus 로고
    • note
    • Note that the real molecule structure most likely will not have such inversion symmetry due to the complicated strain distribution around the dot structures (see also text).
  • 49
    • 20144383782 scopus 로고    scopus 로고
    • note
    • A lateral displacement would also have pronounced effects on the interaction of molecule states that arise from quantum dot states with different angular momenta. For structures without displacement angular momentum remains a good quantum number. As a consequence s- and p-shell molecule states would cross each other when coming into resonance. This could be achieved, for example, for the "antibonding" s-shell and the "bonding" p-shell exciton state when varying the width of the separating barrier. Introducing a lateral displacement breaks the rotational symmetry leading to a mixing of states with different angular momenta, so that these two states would avoid each other when brought into resonance
  • 51
    • 20144368454 scopus 로고    scopus 로고
    • note
    • We note that there has been a report on a negative diamagnetic shift of the ground state exciton emission for self-assembled quantum dots. The results have been obtained by photoluminescence spectroscopy up to B=60 T on a dot array with a rather large inhomogeneous broadening (Ref. 37). This finding was attributed to an increase of the exciton binding energy by B which is larger than the increase of geometric confinement by the magnetic field acting. In the analysis of such data one has to be careful how the field application affects carrier capture into the dot structures. To the best of our knowledge, in measurements on self-assembled single dots with clearly superior resolution only positive diamagnetic shifts have been observed so far. Negative diamagnetic shifts seem possible only for quantum dots in the weak confinement regime, where Coulomb dominates over the geometric confinement.
  • 56
    • 20144372703 scopus 로고    scopus 로고
    • note
    • We note that only fields up to about 15 T have been used in these studies.
  • 59
    • 20144369032 scopus 로고    scopus 로고
    • note
    • 4> has become so large that a magnetic field with strengths comparable to the ones available here cannot bring these levels in resonance.
  • 62
    • 20144362650 scopus 로고    scopus 로고
    • note
    • Alternately, rough estimates for the diamagnetic shift can be obtained by identifying pairs of lines which converge for zero magnetic field after fitting crossing lines to the data at the anticrossing points in the magnetic field dispersions. When doing so, for example, for QDM3 and QDM4 in Fig. 18, one also obtains diamagnetic shift values which fall into the statistics of the data for the respective barrier widths.
  • 66
    • 20144381830 scopus 로고    scopus 로고
    • note
    • In the present samples photoluminescence excitation studies were hampered because of the structure growth on n-doped substrates. From this doping a significant background arises in the energy range of the excited molecule states, from which the molecule signal cannot be separated reliably.
  • 73
    • 14944345830 scopus 로고    scopus 로고
    • Quantum Metrology with Entangled Photons
    • edited by T. J. Quinn, S. Leschiutta, and P. Tavella (IOS Press, Amsterdam)
    • An overview of the potential application of entangled photons, for example in metrology, is given in A. Sergienko, Quantum Metrology with Entangled Photons, in Proceedings of the International School of Physics "Enrico Fermi", Course CXLVI, edited by T. J. Quinn, S. Leschiutta, and P. Tavella (IOS Press, Amsterdam, 2001).
    • (2001) Proceedings of the International School of Physics "Enrico Fermi", Course CXLVI
    • Sergienko, A.1


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.