Visible light emission from innate silicon nanocrystals in an oxide matrix grown at low temperature

Silicon nanocrystals with well-controlled sizes below 5.0 nm at a number density up to 10(12) cm(-2) were directly grown in hydrogenated silicon oxide films by plasma-enhanced chemical vapour deposition using SiH4, O-2 and H-2 as the precursor. For the immediate formation of silicon nanocrystals in deposits on a cold substrate, high-density hydrogen ions have to be maintained in the plasma. These innate silicon nanocrystals are found to be well isolated from each other and dispersed uniformly throughout the deposits. Intense visible photoluminescence was measured at room temperature from such samples, with the photon energy at about 1.67 eV being indifferent to the variation in particle size. The photoluminescence features can find a qualitative explanation in the nearly stabilized electronic states of silicon nanocrystals by Si=O surface-passivation.