Browsing by Author "Braskén, M."

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    Magneto-optical properties of strain-induced InxGa1-xAs parabolic quantum dots
    (American Physical Society (APS), 1998) Rinaldi, R.; Mangino, R.; Cingolani, R.; Lipsanen, Harri; Sopanen, Markku; Tulkki, J.; Braskén, M.; Ahopelto, J.; Department of Micro and Nanosciences; Mikro- ja nanotekniikan laitos; Sähkötekniikan korkeakoulu; School of Electrical Engineering
    We have investigated the Zeeman splitting in strained InxGa1-xAs quantum dots with different quantization energies by means of magnetoluminescence. A multifold splitting of Π and Δ states is observed due to lifted degeneracy of m>0 states. The experimental data were systematically compared to the diamagnetic and Zeeman shift of the single-particle states, taking into account the details of the valence-band structure and the spin splitting. Our data indicate that excitonic effects are negligible and that the magneto-optical properties of these strongly confined dots can be described rather accurately within the single-particle model.
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    Temperature dependence of carrier relaxation in strain-induced quantum dots
    (American Physical Society (APS), 1998) Braskén, M.; Lindberg, M.; Sopanen, Markku; Lipsanen, Harri; Tulkki, J.; Department of Micro and Nanosciences; Mikro- ja nanotekniikan laitos; Sähkötekniikan korkeakoulu; School of Electrical Engineering
    We report experimental observation and theoretical interpretation of temperature-dependent, time-resolved luminescence from strain-induced quantum dots. The experimental results are well described by a master equation model for the electrons. The intraband relaxation in the conduction band and the radiative recombination rate are governed by the hole populations resulting in prominent temperature dependence of the relaxation process. Even when only a few electrons and holes are confined in a single quantum dot the Auger-like process provides a rapid intraband relaxation channel for electrons that can replace the phonon scattering as the dominant relaxation mechanism.