Piezoresistance measurement on single crystal silicon nanowires

摘要

A p-type single crystal silicon nanowire bridge and a four-terminal nanowire element were fabricated by electron-beam direct writing. The piezoresistance was investigated in order to demonstrate the usefulness of these sensing elements as mechanical sensors. The longitudinal piezoresistance coefficient π_(l110) was found to be 38.7×10~(-11) Pa~(-1) at a surface impurity concentration of Ns=9×10~(19) cm~(-3) for the nanowire bridge. The shear piezoresistance coefficient π_(44) was found to be 77.4×10~(-11) Pa~(-1) at Ns=9×10~(19) cm~(3) for the four-terminal nanowire element. These values are 54.8 larger than the values obtained from p~(+) diffused piezoresistors, which are used in conventional mechanical sensors.