Light pulses control graphene’s electrical behavior
Graphene, an ultrathin form of carbon with exceptional electrical, optical, and mechanical properties, has become a focus of research on a variety of potential uses. Now researchers at MIT have found a way to control how the material conducts electricity by using extremely short light pulses, which could enable its use as a broadband light detector. The new findings are published in the journal Physical Review Letters, in a paper by graduate student Alex Frenzel, Nuh Gedik, and three others. The researchers found that by controlling the concentration of electrons in a graphene sheet, they could change the way the material responds to a short but intense light pulse. If the graphene sheet starts out with low electron concentration, the pulse increases the material’s electrical conductivity. This behavior is similar to that of traditional semiconductors, such as silicon and germanium. But if the graphene starts out with high electron concentration, the pulse decreases...