The effects of quantum dot coverage in InAs/(In)GaAs nanostructures for long wavelength emission |
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Authors: | G Trevisi L Seravalli M Prezioso E Gombia L Nasi S Franchi |
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Affiliation: | a CNR-IMEM, Parco delle Scienze 37a, I-43100 Parma, Italy b Laboratorio de Celdas Solares, IMRE, Universidad de La Habana, 10400 La Habana, Cuba |
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Abstract: | We present a study on the effects of quantum dot coverage on the properties of InAs dots embedded in GaAs and in metamorphic In0.15Ga0.85As confining layers grown by molecular beam epitaxy on GaAs substrates. We show that redshifted emission wavelengths exceeding 1.3 μm at room temperature were obtained by the combined use of InGaAs confining layers and high quantum dot coverage. The use of high InAs coverage, however, leads to detrimental effects on the optical and electrical properties of the structures. We relate such behaviour to the formation of extended structural defects originating from relaxed large-sized quantum dots that nucleate in accordance to thermodynamic equilibrium theories predicting the quantum dot ripening. The effect of the reduced lattice-mismatch of InGaAs metamorphic layers on quantum dot ripening is discussed in comparison with the InAs/GaAs system. |
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Keywords: | Quantum dots Long wavelength emission Molecular beam epitaxy Quantum dot ripening |
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