Enhanced light absorption of silicon in the near-infrared band by designed gold nanostructures

A scheme to enhance near-infrared band absorption of a Si nanoparticle by placing the Si nanoparticle into a designed gold nanostructure is proposed. Three-dimensional (3D) finite-difference time-domain simulations are employed to calculate the absorption spectrum of the Si nanostructure and maximize it by generating alternate designs. The results show that in the near-infrared region over 700 nm, the absorption of a pure Si nanoparticle is very low, but when the same nanoparticle is placed within an optimally designed gold nanostructure, its absorption cross section can be enhanced by more than two orders of magnitude in the near-infrared band.