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Circular polarization in a non-magnetic resonant tunneling device.

Dos Santos LF, Gobato YG, Teodoro MD, Lopez-Richard V, Marques GE, Brasil MJ, Orlita M, Kunc J, Maude DK, Henini M, Airey RJ - Nanoscale Res Lett (2011)

Bottom Line: We have investigated the polarization-resolved photoluminescence (PL) in an asymmetric n-type GaAs/AlAs/GaAlAs resonant tunneling diode under magnetic field parallel to the tunnel current.The quantum well (QW) PL presents strong circular polarization (values up to -70% at 19 T).However, the circular polarization degree in the QW also depends on various other parameters, including the g-factors of the different layers, the density of carriers along the structure, and the Zeeman and Rashba effects.

View Article: PubMed Central - HTML - PubMed

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

ABSTRACT
We have investigated the polarization-resolved photoluminescence (PL) in an asymmetric n-type GaAs/AlAs/GaAlAs resonant tunneling diode under magnetic field parallel to the tunnel current. The quantum well (QW) PL presents strong circular polarization (values up to -70% at 19 T). The optical emission from GaAs contact layers shows evidence of highly spin-polarized two-dimensional electron and hole gases which affects the spin polarization of carriers in the QW. However, the circular polarization degree in the QW also depends on various other parameters, including the g-factors of the different layers, the density of carriers along the structure, and the Zeeman and Rashba effects.

No MeSH data available.


Related in: MedlinePlus

Voltage dependence of PL for QW (a) and contact layers (d) under zero magnetic field and polarization resolved PL for QW (b,c) and contact layers (e,f) under 19 T.
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Figure 2: Voltage dependence of PL for QW (a) and contact layers (d) under zero magnetic field and polarization resolved PL for QW (b,c) and contact layers (e,f) under 19 T.

Mentions: Figure 2a presents the voltage dependence of the QW PL at 0 T. The PL intensity increases in the electron resonance region (e1) and decreases after resonant tunneling condition. Therefore, the QW PL intensity presents a good correlation with the electron resonance which is due to the important increase of electron carrier density in the QW under resonant condition. As mentioned earlier, the PL intensity is proportional to the product of the hole and electron densities and, therefore, it is very sensitive to the variation of charge density in the QW (due to accumulated holes or electrons) which results in a modulation of the PL intensity near the resonant voltages. Figure 2b,c presents the voltage dependence of the QW PL intensity under 19 T for both σ+ and σ- polarizations. Under magnetic field, confined levels in the QW and contact layers split into spin-up and spin-down Zeeman states and the optical recombination can occur with well-defined selection rules giving information about the spin polarization of carriers in the structure. We have also observed a good correlation between the PL intensity and I(V) characteristic curve for both polarization σ+ and σ-. We have also observed that the QW emission is highly σ- polarized. The voltage dependence of the polarized degree of this emission will be discussed later in this manuscript.


Circular polarization in a non-magnetic resonant tunneling device.

Dos Santos LF, Gobato YG, Teodoro MD, Lopez-Richard V, Marques GE, Brasil MJ, Orlita M, Kunc J, Maude DK, Henini M, Airey RJ - Nanoscale Res Lett (2011)

Voltage dependence of PL for QW (a) and contact layers (d) under zero magnetic field and polarization resolved PL for QW (b,c) and contact layers (e,f) under 19 T.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211145&req=5

Figure 2: Voltage dependence of PL for QW (a) and contact layers (d) under zero magnetic field and polarization resolved PL for QW (b,c) and contact layers (e,f) under 19 T.
Mentions: Figure 2a presents the voltage dependence of the QW PL at 0 T. The PL intensity increases in the electron resonance region (e1) and decreases after resonant tunneling condition. Therefore, the QW PL intensity presents a good correlation with the electron resonance which is due to the important increase of electron carrier density in the QW under resonant condition. As mentioned earlier, the PL intensity is proportional to the product of the hole and electron densities and, therefore, it is very sensitive to the variation of charge density in the QW (due to accumulated holes or electrons) which results in a modulation of the PL intensity near the resonant voltages. Figure 2b,c presents the voltage dependence of the QW PL intensity under 19 T for both σ+ and σ- polarizations. Under magnetic field, confined levels in the QW and contact layers split into spin-up and spin-down Zeeman states and the optical recombination can occur with well-defined selection rules giving information about the spin polarization of carriers in the structure. We have also observed a good correlation between the PL intensity and I(V) characteristic curve for both polarization σ+ and σ-. We have also observed that the QW emission is highly σ- polarized. The voltage dependence of the polarized degree of this emission will be discussed later in this manuscript.

Bottom Line: We have investigated the polarization-resolved photoluminescence (PL) in an asymmetric n-type GaAs/AlAs/GaAlAs resonant tunneling diode under magnetic field parallel to the tunnel current.The quantum well (QW) PL presents strong circular polarization (values up to -70% at 19 T).However, the circular polarization degree in the QW also depends on various other parameters, including the g-factors of the different layers, the density of carriers along the structure, and the Zeeman and Rashba effects.

View Article: PubMed Central - HTML - PubMed

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

ABSTRACT
We have investigated the polarization-resolved photoluminescence (PL) in an asymmetric n-type GaAs/AlAs/GaAlAs resonant tunneling diode under magnetic field parallel to the tunnel current. The quantum well (QW) PL presents strong circular polarization (values up to -70% at 19 T). The optical emission from GaAs contact layers shows evidence of highly spin-polarized two-dimensional electron and hole gases which affects the spin polarization of carriers in the QW. However, the circular polarization degree in the QW also depends on various other parameters, including the g-factors of the different layers, the density of carriers along the structure, and the Zeeman and Rashba effects.

No MeSH data available.


Related in: MedlinePlus