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Spin effects in InAs self-assembled quantum dots.

Dos Santos EC, Gobato YG, Brasil MJ, Taylor DA, Henini M - Nanoscale Res Lett (2011)

Bottom Line: We have studied the polarized resolved photoluminescence in an n-type resonant tunneling diode (RTD) of GaAs/AlGaAs which incorporates a layer of InAs self-assembled quantum dots (QDs) in the center of a GaAs quantum well (QW).We have observed that the QD circular polarization degree depends on applied voltage and light intensity.Our results are explained in terms of the tunneling of minority carriers into the QW, carrier capture by InAs QDs and bias-controlled density of holes in the QW.

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Affiliation: Physics Department, Federal University of São Carlos, São Carlos, Brazil. yara@df.ufscar.br.

ABSTRACT
We have studied the polarized resolved photoluminescence in an n-type resonant tunneling diode (RTD) of GaAs/AlGaAs which incorporates a layer of InAs self-assembled quantum dots (QDs) in the center of a GaAs quantum well (QW). We have observed that the QD circular polarization degree depends on applied voltage and light intensity. Our results are explained in terms of the tunneling of minority carriers into the QW, carrier capture by InAs QDs and bias-controlled density of holes in the QW.

No MeSH data available.


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PL spectra for different applied voltages at 15 T and 2 K.
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Figure 4: PL spectra for different applied voltages at 15 T and 2 K.

Mentions: Figure 4 shows typical polarized resolved PL spectra from QDs under applied bias and magnetic field (15 T). Under magnetic field, the confined levels splits into spin-up and spin-down Zeeman states and the optical recombination can occurs with well defined selection rules probing the spin polarization of carriers in the structure [10,11]. We clearly observe that the relative intensities from σ+ and σ- QD emission bands vary with the applied bias voltage even though the spin-splitting of the QD PL emission is negligible and does not show any appreciable variation with the applied voltage. Therefore the observed spin splitting does not explain the voltage dependence of the QD polarization degree. In fact, the confined states of the QD should not follow a simple thermal equilibrium statistics, as the polarization of the carriers on those states should also depend on the polarization of the injected carriers, as we discuss below.


Spin effects in InAs self-assembled quantum dots.

Dos Santos EC, Gobato YG, Brasil MJ, Taylor DA, Henini M - Nanoscale Res Lett (2011)

PL spectra for different applied voltages at 15 T and 2 K.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211160&req=5

Figure 4: PL spectra for different applied voltages at 15 T and 2 K.
Mentions: Figure 4 shows typical polarized resolved PL spectra from QDs under applied bias and magnetic field (15 T). Under magnetic field, the confined levels splits into spin-up and spin-down Zeeman states and the optical recombination can occurs with well defined selection rules probing the spin polarization of carriers in the structure [10,11]. We clearly observe that the relative intensities from σ+ and σ- QD emission bands vary with the applied bias voltage even though the spin-splitting of the QD PL emission is negligible and does not show any appreciable variation with the applied voltage. Therefore the observed spin splitting does not explain the voltage dependence of the QD polarization degree. In fact, the confined states of the QD should not follow a simple thermal equilibrium statistics, as the polarization of the carriers on those states should also depend on the polarization of the injected carriers, as we discuss below.

Bottom Line: We have studied the polarized resolved photoluminescence in an n-type resonant tunneling diode (RTD) of GaAs/AlGaAs which incorporates a layer of InAs self-assembled quantum dots (QDs) in the center of a GaAs quantum well (QW).We have observed that the QD circular polarization degree depends on applied voltage and light intensity.Our results are explained in terms of the tunneling of minority carriers into the QW, carrier capture by InAs QDs and bias-controlled density of holes in the QW.

View Article: PubMed Central - HTML - PubMed

Affiliation: Physics Department, Federal University of São Carlos, São Carlos, Brazil. yara@df.ufscar.br.

ABSTRACT
We have studied the polarized resolved photoluminescence in an n-type resonant tunneling diode (RTD) of GaAs/AlGaAs which incorporates a layer of InAs self-assembled quantum dots (QDs) in the center of a GaAs quantum well (QW). We have observed that the QD circular polarization degree depends on applied voltage and light intensity. Our results are explained in terms of the tunneling of minority carriers into the QW, carrier capture by InAs QDs and bias-controlled density of holes in the QW.

No MeSH data available.


Related in: MedlinePlus