The piezoresistance effect of silicon has been widely used in mechanical sensors, and is now being actively explored in order to improve the performance of silicon transistors. In fact, strain engineering is now considered to be one of the most promising strategies for developing high-performance sub-10-nm silicon devices. Interesting electromechanical properties have been observed in carbon nanotubes. In this paper we report that Si nanowires possess an unusually large piezoresistance effect compared with bulk. For example, the longitudinal piezoresistance coefficient along the 111 direction increases with decreasing diameter for p-type Si nanowires, reaching as high as -3,550 10^-11 Pa^–1, in comparison with a bulk value of -94 10^-11 Pa^-1. Strain-induced carrier mobility change and surface modifications have been shown to have clear influence on piezoresistance coefficients. This giant piezoresistance effect in Si nanowires may have significant implications in nanowire-based flexible electronics, as well as in nanoelectromechanical systems.

• < Prev