Large and Pressure-Dependent <i>c-</i>Axis Piezoresistivity of Highly Oriented Pyrolytic Graphite near Zero Pressure.

Wang, Bingjie; Li, Juyao; Fang, Zheng; Jiang, Yifan; Li, Shuo; Zhan, Fangyuan; Dai, Zhaohe; Chen, Qing et al. · Nano Lett · 2024

basic_science · Level V

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Abstract

The <i>c-</i>axis piezoresistivity is a fundamental and important parameter of graphite, but its value near zero pressure has not been well determined. Herein, a new method for studying the <i>c-</i>axis piezoresistivity of van der Waals materials near zero pressure is developed on the basis of <i>in situ</i> scanning electron microscopy and finite element simulation. The <i>c-</i>axis piezoresistivity of microscale highly oriented pyrolytic graphite (HOPG) is found to show a large value of 5.68 × 10<sup>-5</sup> kPa<sup>-1</sup> near zero pressure and decreases by 2 orders of magnitude to the established value of ∼10<sup>-7</sup> kPa<sup>-1</sup> when the pressure increases to 200 MPa. By modulating the serial tunneling barrier model on the basis of the stacking faults, we describe the <i>c-</i>axis electrical transport of HOPG under compression. The large <i>c-</i>axis piezoresistivity near zero pressure and its large decrease in magnitude with pressure are attributed to the rapid stiffening of the electromechanical properties under compression.