The piezoconductive effect of suspended ultrathin graphene film

We study a vertical pressure-modulated conductance of suspended graphene in which the C–C coupling is adjusted by external pressure. Through the tight-binding model and the non-equilibrium Green's function method, the relative piezoconductance is calculated. It is found that the perfect graphene monolayer and multi-layer films have similar piezoconductive properties. When dephasing processes are considered, the multi-layer graphene is fragile, its piezoconductance is dramatically reduced. Concerning the nonideal ohmic contact, the relative piezoconductance is highly layer number dependent. The more layers, the greater the impact. It means the piezoconductive effect is highly affected by the dephasing processes and quality of ohmic contact. Because the dephasing processes and ohmic contact are both the most common factors in experiments, the piezoconductive effect in pressure modulated ultrathin graphene, and its dependance on the dephasing precesses and device fabrication, would help us to understand the electromechanical properties of graphene for future applications.