Ultrasensitive piezoresistive behavior of silicon carbonitride thin films by optimizing nanomorphologies

Abstract

Silicon carbonitride (SiCN)-containing amorphous carbon network is a promising piezoresistive material for pressure sensor due to superior high temperature stability and strong piezoresistive properties. However, current works mainly concerned on bulk SiCN that is unable to satisfy rapid development of large area electronics, and the mechanism of the superior piezoresistive characteristics is still not clear. In this work, SiCN thin films with various carbon concentrations are prepared by magnetron sputtering, and first principles approach is applied to reveal the piezoresistive mechanism of SiCN. The SiCN sample with moderate carbon content features ultrahigh gauge factors range of 1713–7290 under varied stress, which are significantly larger than those of existing piezoresistive thin films. By combining with first principles calculations, it is concluded that the distance between carbon clusters is crucial for piezoresistive effect of SiCN, and a distance of 1.8 Å is optimal for generating tunneling effect and obtaining outstanding piezoresistive performance. Moreover, the influence of carbon concentration on resistance change in experiments is nicely predicted by the bandgap change calculated by first principles, which can be applied to evaluate the nanostructure–property relationship for piezoresistive materials.