L. A. Larsson

Circularly polarized emission from ensembles of InAs/GaAs quantum dots

We present a low-temperature micro-photoluminescence (mu-PL) study of ensembles of InAs/GaAs quantum dots (QDs) with respect to its circular polarization (rho(c)) for a manifold of experimental con ...

Temperature and magnetic field effects on the transport controlled charge state of a single quantum dot.

Individual InAs/GaAs quantum dots are studied by micro-photoluminescence. By varying the strength of an applied external magnetic field and/or the temperature, it is demonstrated that the charge state of a single quantum dot can be tuned. This tuning effect is shown to be related to the in-plane electron and hole transport, prior to capture into the quantum dot, since the photo-excited carriers are primarily generated in the barrier.

Manipulating the spin polarization of excitons in a single quantum dot by optical means

Circular polarization studies of photoluminescence from the neutral (X0) and the positively charged (X+) excitons are reported for individual InAs/GaAs quantum dots (QDs). High polarization degrees, 60% for X0 and 73% for X+, were recorded without any external magnetic field applied. These studies show that the QD polarization and population dynamics are controllable either by varying the photoexcitation intensity or by using a second IR laser excitation.

Quantum Dot Charging By Means Of Temperature And Magnetic Field

A micro‐photoluminescence study of individual InAs/GaAs quantum dots is presented. It is demonstrated that by varying the strength of an applied magnetic field and/or the temperature, the charge state of a quantum dot can be tuned. The charge tuning mechanism is shown to be due to the modification of the electron and hole transport in the wetting layer plane prior to their capture into the quantum dot.

Spin Polarizing Neutral Excitons In Quantum Dots

A high degree of spin polarization for the neutral exciton in individual InAs quantum dots, without any external magnetic field applied, is demonstrated. The polarization mechanism is shown to be due to the difference in capture time into the QD for the electrons and holes after photo excitation in the wetting layer. This leads to optical pumping of the QD nuclei by spin polarized electrons and hence suppression of the anisotropic electron—hole exchange interaction.

Charge State Control Of Single InAs/GaAs Quantum Dots By Means Of An External Magnetic Field

Individual InAs/GaAs quantum dots (QDs) are studied with micro‐photoluminescence in the presence of an applied external magnetic field. Attention is focused on the redistribution between the spectral lines of a single QD observed at increased external magnetic field when the magnetic field is applied parallel to the growth direction (Faraday geometry). The effect is shown to be transport related as the electron drift velocity in the QD‐plane is decreased by the applied magnetic field and this affects the probability for electron capture into the QD.