Time-resolved cathodoluminescence of InGaAs/AlGaAs tetrahedral pyramidal quantum structures |
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Authors: | M Merano S Sonderegger A Crottini S Collin E Pelucchi P Renucci A Malko MH Baier E Kapon JD Ganière B Deveaud |
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Institution: | (1) Institute of Quantum Electronics and Photonics, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland |
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Abstract: | An original time resolved cathodoluminescence set up has been used to investigate the optical properties and the carrier transport
in quantum structures located in InGaAs/AlGaAs tetrahedral pyramids. An InGaAs quantum dot formed just below the top of the
pyramid is connected to four types of low-dimensional barriers: InGaAs quantum wires on the edges of the pyramid, InGaAs quantum
wells on the (111)A facets and segregated AlGaAs vertical quantum wire and AlGaAs vertical quantum wells formed at the centre
and at the pyramid edges. Experiments were performed at a temperature of 92 K, an accelerating voltage of 10 kV and a beam
probe current of 10 pA. The cathodoluminescence spectrum shows five luminescence peaks. Rise and decay times for the different
emission wavelengths provide a clear confirmation of the peak attribution (previously done with other techniques) to the different
nanostructures grown in a pyramid. Moreover, experimental results suggest a scenario where carriers diffuse from the lateral
quantum structures towards the central structures (the InGaAs quantum dot and the segregated AlGaAs vertical quantum wire)
via the InGaAs quantum wires on the edges of the pyramid. According to this hypothesis, we have modeled the carrier diffusion
along these quantum wires. An ambipolar carrier mobility of 1400 cm2/V s allows to obtain a good fit to all temporal dependences.
PACS 78.67.-n |
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