Silicon is widely used for solar energy harvesting applications. Here we investigate the dynamics and transport properties of photoexcited carriers in silicon nanowires by ultrafast terahertz spectroscopy. The carrier lifetime was observed to approach 0.7 ns, and the carrier mobility to be ∼1000 cm 2/(Vs). We found that Silicon nanowire arrays fabricated by the metal-assisted chemical etching is better for solar cell application. © 2013 IEEE.