Magneto-optical effects in photoluminescence of Si nanocrystals

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Abstract
We report on magneto-optical studies of excitons confined in Si nanocrystallites. As a result of Zeeman splitting of the exciton ground level the whole resonantly excited photoluminescence spectrum shifts linearly to lower energy with rising magnetic field. The recombination decay time depends on magnetic field due to the change in the thermal populations of singlet-triplet sublevels of the exciton ground state. The effect is stronger for weakly confined excitons when the value of the Zeeman splitting becomes comparable with the electron-hole exchange energy. The experimental results strongly support the exciton nature of luminescing states responsible for the light emission from porous silicon.