Giant piezoresistance effect in silicon nanowires

The piezoresistance effect of silicon1 has been widely used in mechanical sensors2–4, and is now being actively explored in order to improve the performance of silicon transistors5, 6. In fact, strain engineering is now considered to be one of the most promising strategies for developing high-performance sub-10-nm silicon devices7. Interesting electromechanical properties have been observed in carbon nanotubes8, 9. 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. Straininduced 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. © 2006 Macmillan Publishers Limited. All rights reserved.