Efficient intraband optical transitions in Si nanocrystals

Efficient intraband optical transitions in the infrared range are predicted in n-type Si nanocrystals using tight-binding calculations of no-phonon and one-phonon-assisted processes taking into account each vibrational mode. New types of transitions are reported, with no equivalence in direct gap semiconductors, between the confined states in the six valleys of the conduction band. They involve phonons with wave vectors either at the center or at the edge of the Brillouin zone. The efficiency of the main no-phonon and phonon-assisted transitions is comparable to the one in III-V semiconductor quantum dots.