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Magnetoluminescence from trion and biexciton in type-II quantum dot.

Okuyama R, Eto M, Hyuga H - Nanoscale Res Lett (2011)

Bottom Line: Since the relative motion of electrons are frozen, the Wigner molecule behaves as a composite particle whose mass and charges are twice those of an electron.As a result, the period of AB oscillation for trion and biexciton becomes h/2e as a function of magnetic flux penetrating the ring.We find that the magnetoluminescence spectra from trion and biexciton change discontinuously as the magnetic flux increases by h/2e.PACS: 71.35.Ji, 73.21.-b, 73.21.La, 78.67.Hc.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. rokuyama@rk.phys.keio.ac.jp.

ABSTRACT
We theoretically investigate optical Aharonov-Bohm (AB) effects on trion and biexciton in the type-II semiconductor quantum dots, in which holes are localized near the center of the dot, and electrons are confined in a ring structure formed around the dot. Many-particle states are calculated numerically by the exact diagonalization method. Two electrons in trion and biexciton are strongly correlated to each other, forming a Wigner molecule. Since the relative motion of electrons are frozen, the Wigner molecule behaves as a composite particle whose mass and charges are twice those of an electron. As a result, the period of AB oscillation for trion and biexciton becomes h/2e as a function of magnetic flux penetrating the ring. We find that the magnetoluminescence spectra from trion and biexciton change discontinuously as the magnetic flux increases by h/2e.PACS: 71.35.Ji, 73.21.-b, 73.21.La, 78.67.Hc.

No MeSH data available.


The luminescence peaks from (a) exciton and (b) trion in the type-II semiconductor quantum dot, as a function of the magnetic flux Φ. The trion peak suddenly drops as Φ increases by h/2e.
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Figure 4: The luminescence peaks from (a) exciton and (b) trion in the type-II semiconductor quantum dot, as a function of the magnetic flux Φ. The trion peak suddenly drops as Φ increases by h/2e.

Mentions: We examine recombination phenomena. Figure 4 shows the Φ dependence of the luminescence peak from (a) exciton and (b) trion. The behavior of the biexciton peak is qualitatively the same as in Figure 4b. The exciton peak oscillates by the period of about h/e. On the other hand, the trion peak increases with an increase in Φ and suddenly drops by the period of about h/2e. The fractional period of h/2e comes from the period of AB oscillation in the ground state of trion. The discontinuous change is explained by a selection rule for the recombination: The optical transition conserves the orbital angular momentum in two-dimensional systems [11]. A trion with the angular momentum L has to decay into an electron with the same angular momentum. As a result, both of the initial and final states of the recombination change at the transition of the trion state. In the case of exciton recombination, the final state is always the vacuum state of the quantum dot, and the peak position is continuous as a function of Φ, as seen in Figure 4a (The recombination of exciton with the angular momentum L ≠ 0 is forbidden by a selection rule. After the first transition of the electronic state at Φ ≄ h/2e, excitons get dark in our model. However the forbidden transitions were observed in experiments. This should be ascribed to the disorder of samples which breaks the selection rule.)


Magnetoluminescence from trion and biexciton in type-II quantum dot.

Okuyama R, Eto M, Hyuga H - Nanoscale Res Lett (2011)

The luminescence peaks from (a) exciton and (b) trion in the type-II semiconductor quantum dot, as a function of the magnetic flux Φ. The trion peak suddenly drops as Φ increases by h/2e.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211441&req=5

Figure 4: The luminescence peaks from (a) exciton and (b) trion in the type-II semiconductor quantum dot, as a function of the magnetic flux Φ. The trion peak suddenly drops as Φ increases by h/2e.
Mentions: We examine recombination phenomena. Figure 4 shows the Φ dependence of the luminescence peak from (a) exciton and (b) trion. The behavior of the biexciton peak is qualitatively the same as in Figure 4b. The exciton peak oscillates by the period of about h/e. On the other hand, the trion peak increases with an increase in Φ and suddenly drops by the period of about h/2e. The fractional period of h/2e comes from the period of AB oscillation in the ground state of trion. The discontinuous change is explained by a selection rule for the recombination: The optical transition conserves the orbital angular momentum in two-dimensional systems [11]. A trion with the angular momentum L has to decay into an electron with the same angular momentum. As a result, both of the initial and final states of the recombination change at the transition of the trion state. In the case of exciton recombination, the final state is always the vacuum state of the quantum dot, and the peak position is continuous as a function of Φ, as seen in Figure 4a (The recombination of exciton with the angular momentum L ≠ 0 is forbidden by a selection rule. After the first transition of the electronic state at Φ ≄ h/2e, excitons get dark in our model. However the forbidden transitions were observed in experiments. This should be ascribed to the disorder of samples which breaks the selection rule.)

Bottom Line: Since the relative motion of electrons are frozen, the Wigner molecule behaves as a composite particle whose mass and charges are twice those of an electron.As a result, the period of AB oscillation for trion and biexciton becomes h/2e as a function of magnetic flux penetrating the ring.We find that the magnetoluminescence spectra from trion and biexciton change discontinuously as the magnetic flux increases by h/2e.PACS: 71.35.Ji, 73.21.-b, 73.21.La, 78.67.Hc.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. rokuyama@rk.phys.keio.ac.jp.

ABSTRACT
We theoretically investigate optical Aharonov-Bohm (AB) effects on trion and biexciton in the type-II semiconductor quantum dots, in which holes are localized near the center of the dot, and electrons are confined in a ring structure formed around the dot. Many-particle states are calculated numerically by the exact diagonalization method. Two electrons in trion and biexciton are strongly correlated to each other, forming a Wigner molecule. Since the relative motion of electrons are frozen, the Wigner molecule behaves as a composite particle whose mass and charges are twice those of an electron. As a result, the period of AB oscillation for trion and biexciton becomes h/2e as a function of magnetic flux penetrating the ring. We find that the magnetoluminescence spectra from trion and biexciton change discontinuously as the magnetic flux increases by h/2e.PACS: 71.35.Ji, 73.21.-b, 73.21.La, 78.67.Hc.

No MeSH data available.