Quantum confinement in porous silicon

Two emission bands were simultaneously observed in iron-passivated porous silicon and their peak energies were in good agreement with the first two gap energies calculated for silicon nanocrystallites $(nc-\mathrm{Si}).\mathrm{}$ This result indicates the existence of separate conduction subbands caused by the quantum confinement of carriers in $nc-\mathrm{Si}.$ It was also found that under the frame of the quantum confinement effect, the distribution of the photoluminescence intensity over emission wavelength could be well explained by the size distribution of $nc-\mathrm{Si}.$ These facts support the quantum confinement model of the luminescence in porous silicon.