The authors report on room temperature photoluminescence from single CdSe quantum dots. The quantum dots, realized by self-organized epitaxial growth, are embedded in ZnSSe∕MgS barriers. The integrated intensity of the emission drops by less than a factor of 3 between 4K and room temperature. Microphotoluminescence with a spatial resolution of 200nm exhibits single dot emission that remains visible up to 300K. The linewidth of the single dot emission increases thereby from 340μeVto25meV at room temperature, which the authors attribute to the interaction of excitons with optical phonons.

We present a green emitting single quantum dot light emitter integrated into a resonant-cavity diode design. Most important, electroluminescence stemming from one individual quantum dot is obtained at room temperature with a surprisingly low operation voltage of 2.6V. This demonstrates that our single quantum dot device is ideally suited for electrically driven nonclassical light generation under ambient conditions.

The authors report on efficient spin injection from a n-Zn0.96Mn0.04Se layer into an InAs single quantum dot (SQD) in a p-i-n diode structure using magnetomicrophotoluminescence experiments. A circular polarization degree of up to 60% at B=5T is obtained from the InAs single dot emission while no polarized light is observed in a structure with no electrical doping of any of its layers. A pronounced dependence of the spin injection efficiency on the external bias is found resulting in a strong decrease of the SQD circular polarization degree when the biasing is applied in the forward direction. The experiments emphasize the impact of excess energy and current flow on the spin injection efficiency in a SQD.

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We demonstrate electrically driven spin injection into a single semiconductor quantum dot. Spin polarized electrons are transferred from a diluted magnetic semiconductor ( ZnMnSe ) into InAs quantum dots embedded into GaAs barriers. The spin information can be extracted directly from the polarization degree of the electroluminescence signal stemming from an individual quantum dot. By slightly modifying the device design, we demonstrate a concept to electrically charge the quantum dot by a spin polarized electron and present a simple way to probe this spin state optically.

We demonstrate electrical spin‐injection into a single InAs quantum dot embedded in a GaAs‐based p–i–n diode structure using a diluted magnetic semiconductor (ZnMnSe) as a spin‐source. The spin‐information can be extracted directly by evaluating the polarisation degree of the single quantum dot electroluminescence signal. We obtain a spin‐polarisation up to 100% at T = 5 K that is decreasing with higher temperature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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