Silicon nanowires have been demonstrated as one of the promising building blocks for future nano-devices such as FETs, solar cells, sensors and lithium batteries. The nanowire field effect transistor is one candidate which has the potential to overcome the problems caused by short channel effects in SOI MOSFETs and has gained significant attention from both device and circuit developers. In addition to the effective suppression of short channel effects due to improved gate strength and increased packing density, the multi-gate silicon nanowire FETs show excellent current drive and have the merit that they are compatible with conventional CMOS processes.