Piezoresistance in Si3N4 nanobelts: toward highly sensitive and reliable pressure sensors

Abstract

To achieve precision instrumentation and accurate measurement, there is increasing need for pressure sensors to be well serviced in harsh environments. We report, for the first time, piezoresistance in single-crystalline Si₃N₄ nanobelts by conductive atomic force microscopy (C-AFM). The transverse electromechanical properties of the Si₃N₄ nanobelt were investigated under various loading forces applied by the C-AFM tip. The calculated transverse piezoresistance coefficient π_[10] of the nanobelt was in the range of 2.2 to 8.8 × 10⁻¹¹ Pa⁻¹ under the applied loading forces ranging from 25.6 to 135.3 nN. The relationship between the piezoresistance coefficients and the applied forces was almost linear. Significant and linear decreases in nanobelt resistance with increasing loading forces were observed, which exhibited a variation of ∼3 MΩ with a changed force of 1 nN, implying that the pressure sensors have high sensitivity. Stable and repeatable I–V curves through multiple voltage sweepings were accomplished, suggesting that the Si₃N₄ nanobelts pressure sensors are quite reliable.