Quantum confinement effect in crystalline silicon quantum dots in silicon nitride grown using SiH4 and NH3

Crystalline silicon quantum dots (Si QDs) were spontaneously grown in the silicon nitride films by plasma-enhanced chemical vapor deposition using SiH4 and NH3 as precursors. When the size of the Si QDs was reduced from 4.9 to 2.9nm, the photoluminescence peak energy was shifted from 1.73 to 2.77eV. The photoluminescence peak energy was fitted to the relationship, E(eV)=1.13+13.9∕d2, where d is the diameter of the Si QD in nanometers. The measured band-gap energies of the Si QDs were in good agreement with the quantum confinement model for crystalline Si QDs. These results suggest that the hydrogen dissociated from NH3 plays an important role in improving the crystallinity and surface passivation of Si QDs.