Faculty of Science and Technology

The light emitted by silicon nanocrystals comes mostly from defects within the nanocrystals, according to a paper published online this week in Nature Nanotechnology.

Silicon dominates the electronics industry, but other semiconductor materials with better optical properties are preferred for applications in photonics. Until now the way in which silicon emits light has been a bit of a mystery, frustrating efforts to exploit it in optical applications.

Manus Hayne of Lancaster University's Department of Physics, and co-workers investigated whether the light emitted by tiny crystals of silicon embedded in silicon dioxide came from defects or was due to quantum effects confining particles inside the nanocrystals.

By measuring the emission of light when their silicon samples were placed in a strong magnetic field, they were able to show that the light emission was dominated by defects.

The team then exposed the silicon to hydrogen, which made the defects inactive, and the nature of the light changed to reflect the fact that quantum-confinement effects were responsible for the emission.

Subsequently, when the silicon was exposed to ultraviolet light to remove the hydrogen, the defects reappeared and dominated the light emission again. As photons replace electrons in various devices, a better understanding of the optical properties of silicon could allow it to compete with other materials.

Mon 17 March 2008

Associated Links

• Dr Manus Hayne - Lecturer and Research Councils UK Academic Fellow in Experimental Nanoscience