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Carrier Diffusion in the Barrier Enabling Formation of Charged Excitons in InAs/GaAs Quantum Dots

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Karlsson K., Moskalenko E., Holtz P., Monemar B., Schoenfeld W., Garcia J., Petroff P.

Acta Physica Polonica A

2001

vol. 100

issue 3

387-395

It is demonstrated that the photoluminescence spectra of single self-assembled quantum dots are very sensitive to the experimental conditions, such as excitation energy and crystal temperature. A qualitative explanation is given in terms of the effective diffusion of the photogenerated carriers, determined by the experimental conditions, which influence the capture probability and hence also the charge state of the quantum dots. This is proposed as a new tool to populate quantum dots with extra electrons in order to study phenomena involving charged excitons.

Fermi-Edge Singularity in Excitonic Spectra of Modulation Doped AlGaAs/GaAs Quantum Wells

100%

Bugajski M., Regiński K., Godlewski M., Wesołowski M., Holtz P., Buyanov A., Monemar B.

Acta Physica Polonica A

1996

vol. 90

issue 4

751-754

The dynamic response of an electron Fermi sea to the presence of optically generated holes gives rise to an enhanced interaction of correlated electron-hole pairs near the Fermi level, resulting in an enhanced oscillator strength for optical transitions, referred to as the Fermi-edge singularity. We studied this effect in modulation-doped quantum wells which provide confined dense Fermi sea, spatially separated from dopant atoms, easily accessible for investigations under low excitation conditions. The Fermi-edge singularity was observed in both photoluminescence and photoluminescence excitation experiments, although in the case of photoluminescence the samples had to be either co-doped with acceptors in the wells to provide necessary localization of holes or designed to allow for nearly resonant scattering between the electronic states near the Fermi energy and the next unoccupied subband of the 2D electron gas.

Fermi-Edge Singularity in Luminescence Spectra of P-Type Modulation Doped AlGaAs/GaAs Quantum Wells

100%

Bugajski M., Godlewski M., Regiński K., Holtz P., Bergman J., Monemar B.

Acta Physica Polonica A

1998

vol. 94

issue 2

265-270

We have studied an enhancement of the oscillator strength for optical transitions near the Fermi energy in p-type modulation-doped quantum wells, which, so far, deserved much less attention than analogous n-type systems, because of the complicated valence band structure involved. The relatively wide (L=150 Å) quantum wells and high doping levels were used, containing more than one occupied subband. The enhancement in the photoluminescence intensity at the Fermi energy resulted from the strong correlation and multiple scattering of holes near the Fermi edge by the localized electrons.

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3 Acta Physica Polonica A

1 2001

1 1998

1 1996

3 Holtz P.

3 Monemar B.

2 Bugajski M.

2 Godlewski M.

2 Regiński K.

1 Bergman J.

1 Buyanov A.

1 Garcia J.

1 Karlsson K.

1 Moskalenko E.

1 Petroff P.

1 Schoenfeld W.

1 Wesołowski M.

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Carrier Diffusion in the Barrier Enabling Formation of Charged Excitons in InAs/GaAs Quantum Dots

Fermi-Edge Singularity in Excitonic Spectra of Modulation Doped AlGaAs/GaAs Quantum Wells

Fermi-Edge Singularity in Luminescence Spectra of P-Type Modulation Doped AlGaAs/GaAs Quantum Wells