Visible light emitting devices with Schottky contacts on silicon   nanocrystals
  We have fabricated light emitting diodes (LEDs) with Schottky contacts on Si-nanocrystals formed by simple techniques as used for standard Si devices. Orange electroluminescence (EL) from these LEDs could be seen with the naked eye at room temperature when a reverse bias voltage was applied. The EL spectrum has a major peak with a photon energy of 1.9 eV and a minor peak with a photon energy of 2.2 eV. Since the electrons and holes are injected into the radiative recombination centers related to nanocrystals through avalanche breakdown, the voltage needed for a visible light emission is reduced to 4.0 - 4.5 V, which is low enough to be applied by a standard Si transistor. 
S. Fujita and N. Sugiyama (Toshiba Corporation)