EXCITONS IN SILICON NANOCRYSTALLITES

Recombination and binding energies of excitons in nanocrystalline sili con quantum dots are calculated within the effective mass approximatio n including the effects of the induced electrostatic polarization. The calculated exciton recombination energies compare well with other cal culations and with the results from photoluminescence measurements in porous silicon. The calculated exciton binding energies are far larger than the bulk exciton binding energy and show substantial dependence on the matrix that surrounds the nanocrystallites. A model is proposed that explains the main orange-red. blue and infrared luminescence pea ks of porous silicon within a simple unified framework. (C) 1997 Acade mic Press Limited.