Thermally stimulated exciton emission in Si nanocrystals

By laser heating silicon nanocrystals, researchers have more than tripled the emission rate of photons from silicon. Silicon is the most critical semiconductor for use in electronic devices and solar cells, but it suffers from poor optical properties, including low rates of light absorption and photon emission. Now, Elinore de Jong of the University of Amsterdam and co-workers have boosted the photon emission rate by over 300% by laser-induced heating silicon nanocrystals embedded in silica. Simulations revealed that this effect, which is the opposite to that observed in bulk silicon, occurs because the intense laser illumination generates large amounts of phonons. The finding demonstrates that the optical properties of silicon nanocrystals can be tailored and enhanced through the judicious control of their temperature.