First-Principles Simulation on Orientation Dependence of Piezoresistance Properties in Silicon Nanowires

Abstract

We simulated the piezoresistance coefficients in p- and n-type H-terminated <111> silicon nanowire (SiNW) on the basis of first-principles calculations in order to discuss the dependence of the piezoresistive properties on crystallographic orientation, in comparison with the results of calculation for H-terminated SiNWs of other orientations reported in our previous paper. For the p-type <111> SiNW, the hole conductivity depends only on the hole mobility of the highest valence-band subband. As a result, the longitudinal and transverse piezoresistance coefficients for p-type H-terminated <111> SiNW are very small, in contrast to those in the case of p-type bare-walled <111> SiNW with dangling bonds. In the n-type conduction, piezoresistance coefficients are also much smaller than the longitudinal one for the p-type <001> SiNW model. We predict that <111> SiNW will be not a suitable candidate for nanoscale piezoresistors.